Some more information found from Warseer and BoLS that gives more insight to the Nids' codex.  Remember, this is all pre-release information and what is said here is not to be taken as set in stone.  Reading all of this makes me think that the Nids didn't get nearly as much anti-mech firepower as we had anticipated (though the Tyrannofex/Zoanthropes have great shooting!) but if they can get into close combat relatively intact, they are going to wreck someone's day.  And with the numbers

Units

Headquarters
Hive Tyrant, Alpha Warrior, Tervigon.
Named HQs: A special Hive Tyrant, A parasite-spreading winged horror.

Hive Tyrant: Initiative 6, WS:8. Starts of with a pair of Scything talons, a Tentacle whip and a Bonesword. May be given wings or heavy carapace (2+ armour save). May be given a Tyrant guard.

Hive Tyrant variant called the Swarmlord. Armed with 4 Boneswords (see rules above), and loaded up with special rules but costs more than a Land Raider.


May chose from 4 different psychic powers:

-Mental Scream: All enemy units within 18 " have to pass a morale check. if they fail it, they suffer the difference between the roll and their morale characteristic as casulties with no armour saves allowed.
-Lifeleech: One unit within 12 " suffers D3 S:3 AP:2 hits. For each casualty they suffer, the Hive Tyrant gains one wound, up to a maximum of 10.
-Power 3: Forces a unit to pass a morale check or to fall back.
-Power 4: A shooting attack.

Tyrant may be given special abilities, such as the bility to grant another unit outflank and +1 to reserve rolls.

Many weapon options available.

Special Hive Tyrant: WS:9. Invulnerable saves passed versus wounds inflicted by him must be re-rolled. He may give one unit within 18" Prerfered enemy, Furious charge or two other USRs.

Alpha Warrior: WS:6, granted to any unit of Warriors he joins.

Tervigon: Creates 3d6 Termagaunts with standard loadout each movement phase, even in close combat. If killed, gaunts nearby suffer heavy losses. It has its own psychic powers.

The Horror "The Parasite of Mortrex": Winged hit-and-run monster. Every enemy unit outflanking may suffer casualties. The outflanking unit picks one model, and must pass a toughness test. If failed the model is removed and the Tyranid player gets D6 Ripper swarms. The Horror does the same to victims he kills in assault.

Elites
Hive Guard: Unit size 1-3, BS:4 Weapons are 24" S:8 AP:4 Assault 2.

Lictors: 1-3 per FOC slot, acting together as one unit. Lictors deploy like Marbo. Grant +1 to reserve rolls. Deep striking units do not scatter if deployed within 6 inces of a Lictor, as long as it was on the table for at least one turn.

Ymgarl Genestealers: Biomorphable Genestealers. They may increase Attacks, Toughness, or Strength at the beginning of each assault phase. "Hibernation" rule: Pick a piece of terrain. When the Genestealers enter play, they are placed in the selected terrain. The unit may move, shoot and charge. Unit size: 5-10. No Broodlord option.

Zoanthropes: Unit size 1-3. Warp field grants 3+ invulnerable save.
Two psychic powers:
-Warp lightning: S:6 AP:3 3 blast
-Warp lance: 18" S:10 AP:2 Assault 1, lance

Special Zoanthrope "The Doom of Malantai": Leeches wounds with a powerful  5" blast shooting attack. S is equal to current number of Wounds, max of 10.

Death Leaper: WS:9, I:7. Deployed like a lictor, but may retreat and be replaced text turn. ~???

Troops
Hormagaunts: WS:3, S:3, I:5, A:2. Infantry. May be given poison and adrenalin glands. Unit size 10-30

Gaunts: Weapon is S:4 AP:5 Assault 1. For each 10 gaunts, one may be upgraded to a S:2 template that wounds against the target's Strength ~Sounds like tanglewebs return.

Warriors: WS:5, Many options. 4+ Armor save.

Genestealers: Mostly the same, but with less options. Cheaper than Grey Hunters, though. Armor save canot be increased. Infiltrate and Fleet.

Broodlord retains his statline, at a point cost of a Long Fang with a heavy bolter.
May have two psychic powers:
-Confusion: Both players roll a D6 and add the Ld of a model chosen by the Tyranid player. If the Tyranid total is the same or higher, the enemy targeted model may not attack in this close combat phase.
-Ability 2: Reduces the Ld of surrounding enemies by 1.

Fast Attack
Winged Warriors

Gargoyles:
Harpies: Flying, Trygon-sized creature that acts as a bomber. It drops Spore mines on a unit it flies over. Monstrous creature.

Raveners: Two pairs of scything talons. May have a thorax swarm: a special weapon, with ammo chosen at the start of the game. Three flamer variants.

Heavy Support
Carnifexes: Unit size: 1-3. Must have the same loadout. Cannot boost initiative, probably cannot improve armor past 3+. Gain +1 I when charging. Adrenaline glands give I:4 and S:10. Basic WS:3 S:9, W:4 2 pairs of scything talons, A:4.

Trygon: WS:6, S:6, W:6 A:6. Shooting attack: 12" S:6, AP:5 Assault 6. Deep Strike. Trygon cannot assault a unit he Deeps Strikes onto. Follows the same rules as Drop Pods, i.e. stopping within 1".
If upgraded to a Alpha Trygon, weapon becomes 18" Assault 12.

Tyrannofex: Walking weapon battery.
-Fleshborer swarm: S:4 AP:5 Assault 20
-Pyroacid spray: S:6 AP:4 template, used like the IG Hellhound.
-Capsule cannon: 48' S:10, AP:4, Assault 2 
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Dedicated Transports

Spore Capsule: Many units may purchase a Spore Capsule. Occupancy:1 Monstrous Creature, or 20 Infantry. Deep Strike. Disembarking unit may not move or assault. It may shoot.

STATLINE: WS:2 BS:2. T:5-6 W:3 A:3 S:6.
Weapon: 6" S:6 Assault 6.
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RANGED WEAPONS

Venom Cannon
R:36 S:6 AP:4 Assault 1 Blast
-1 modifier on the vehicle damage chart

Heavy Venom Cannon
R:48 S:9 AP:4 Assault 1 Blast
-1 modifier on the vehicle damage chart

Barbed Strangler
R:24 S:4 AP:6 Assault 1 Large Blast

Stranglethorn Cannon
R:36 S:6 AP:4 Assault 1 Large Blast

Spinefist
R:18 S:4 AP:5 Assault X
(X= bearer's number of attacks), twin-linked

Fleshborer
R:18 S:4 AP:5 Assault 1

Sting Blaster
R:12 S:5 AP- Assault 1

Spike Blaster
R:18 S:5 AP:5 Assault 4

Texorin Bug
3 fire modes, may be fired additionally to all other weapons
-Template S:* AP- Assault 1, wounds on 2+ vs. non-vehicles
-Template S:5 AP:5 Assault 1
-Template S:3 AP:6 Assault 1, Rending

Death Blaster
R:18 S:5 AP:5 explosive

BIOMORPHS

Toxin Sacs
ALL units may buy these. Grants Poison attacks (4+)

Adrenal Gland
ALL units may buy these. Grants Furious Charge

Spore Launcher
Big bugs only. Grants Frag granades

Injectors
To-wound rolls of 6 cause the loss of all wounds instead of one

Flesh Hooks
R:6 S:5 AP- Assault 2

Toxic Blood
When the model loses a wound in assault the model causing the wound must pass an I check or lose a wound with no armor save allowed. Vehicles suffer a glancing hit on a 4+

Toxic Miasma
Enemy models in assault range pass a T check or lose one wound with normal armor saves allowed

Lashwhips
All enemy models in assault are reduced to I:1

Chitin Upgrades
From 6+ Armor save to 2+, with several variants

Boneswords
A model suffering a wound tot he weapon must pass an Ld test or is killed outright. If the bearer has a pair of Boneswords the Ld test is made on 3D6.

Scything Talons
Reroll to-hit rolls of 1 in assault, models with a pair of talons reroll all  failed to-hit rolls

Rending Claws
Grant Rending USR in assault

Crushing Claws
Model I is lowered to 1, +D3 Attacks

Regeneration
At the start of each turn the model regains a lost wound on a 6

Wings
Model counts as Jump Infantry
 
 
The release of the Tyranids will hopefully break open the slew of mechanized warfare.  Ideally, although I love mechanized armies and the speed/protection they provide me, I don't want to have to face them every game.  Where are the hordes of old that used to plague the hobby?  Hopefully, this launch of xenos filth will start an avalanche of footbased armies to break up the type of opponents you might face.  Plus, the Nids have needed a re-tune for quite a while now.  :)

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Hormagaunts: Improved Initiative. Point costs halved.

Gaunts: nothing new there.

Gargoyles: A poisoned attack that excactly works as the Warhammer Fantasy Poisoned attacks rule work: Each roll of 6 to hit always wounds. Armour saves applied normally. Poison glands available. Point Costs halved.

Raveners: Plastic Kits of three with lots of options for thorax weapons.

Tyranid Warriors: Improved armoursaves, 3 Lifepoints each. ~Wounds Core unit. You still may have Tyrant Warrior Alphas as HQ choices.

Lictor: 3 for a FOC, no 0-1 Limit. 3 Lifepoints. ~Wounds

Lictor Death Leaper: In the list. WS9, I 7, Rending on 5+.

Old One Eye: In the list.

Red Terror: NOT in the list.

Hive Tyrand: The major HQ choice again.

Hive Guard: Harpoon Cannon does not need LOS. Longe Range weapon.
From a different angle, they really do NOT look like Centaurs at all. They just lean on their middle limbs to balance, bud they really are not 2 pairs of legs.

Genestealers: Point costs dropped. No info if they are core or elite.

Broodlord: Upgrade to all Genestealer squads. Psychic powers.

Venomthrope: Poisoned Attacks that wound on 2+. Grants 5+ cover save to all models within 6 inches.

Pyrovore: Melee Monster with flaming template weapon.

Zoanthrope: Apperantly no 0-1 choice any more.

Carnifexes: Squads of up to 3. Increased ballistic skills.

Trygon: He's there. Monstrous Creature.

Mawloc: He's there too.

At least two new bioweapons: a canon (Hive Guard and/or Pyrovore) and a thorax swarm (Pyrovore?).

Broodlord no HQ (still hoping for Broodlord Alpha being one).

Ravenors compatible sizewise with Warriors (was said before IIRC)

Carnifex gets more attacks and better BS. Broods of 3 confirmed.

Biomorphs for Gargoyles not included but sprue available separately (most people will have enough from the gaunts boxes). "Venom rending" confirmed (automatic wound on 6).

Trygon same size as FW one (see attached pic, my trygon based on a CD). Monstrous creature, parts compatible with carnifex. Will form tunnel swarm together with Ravenors. Will get Apocalypse data sheets in WD Ferbuary. Alpha Trygon Synapse.

Mawloc (German Morgon!) shock troop, can fall back, can borrow/disappear during movement phase just to shock back next round. If Mawloc base shocking in contact with enemy base, place 5" template above and everyone in contact with it will get S6 AP2 hit.

Pyrovore called cc monster with said acid spray attack, but personally I am still convinced of the second artillery attack. GW suggests to also use Pyrovore counting as big Biovore.

Broodlord and Warriors removed from HQ, leaving the lone Hive tyrant (still hoping for Alpha variants).

Tyrant guard gets frenzy and another rule, if Hive Tyrant is killed.

Lictor not 0-1 anymore, one more life, cheaper. Death leaper in Codex with some special rules and mail order only.

Red Terror not rulewise in Codex (just mentioned), model can be used counting as Ravenor.

Zoanthrope has "long range" anti-tank (longer than before?).


"I think this codex may be the beginning of the end of melta-spam" -- Bigred
 
 
If you take a look at the Warhammer 40k section of the Games Workshop site, you will notice they have released the pre-order kits for the Nids.  And might I say, they are beautiful!  Makes me want to take one of those Trygon/Mawlocs and paint it up for laughs.  Perhaps even a Venomthrope.  I need something to break me out of my current painter's block...its not that I need inspiration, just overwhelmed.  :D

However, there has been a little headway on a few of my Black Templars.  More specifically, the meltagun users for my Crusader squads.  I changed their livery a bit for the Njesta Crusade after I painted my first squad in standard colors.  Felt that this new scheme makes them more distinct, especially on the battlefield.  I got positive comments on it from my roommate, who is also a painter (upcoming Golden Daemon painter me-thinks).  I encourage comments on the scheme once I get some pictures up, but at the moment, its proving difficult as I don't have a camera available to me that can take decent macro photos.

Anyways, back to the previous topic:  Tyranids.  These guys look like they will have some of their power returned to them.  While it doesn't look like they will gain any "vehicular" mobility, they seem to have gained quite a bit more in the way of infiltration, scout moves, and outflanking units if the fluff provided by GW is any indication.  This can help negate the 5e cons of being footbased.  The Pyrovore seems to be the Nids answer to Mech, but time will definitely tell.  Either way, I'll be happy to see an influx of xenos players on the scene as its currently a very thin player base.