Yep, the codex is leaked in its entirety already. Normally this would be a bit tricky, because it would take time to scan all of the pages, etc… except that with the new GK book, there's hardly anything in there to scan. So yeah, let's the steaming pile of garbage that we've been served up.
Oh, and before everyone gets all whiney about how I'm just being negative because of the new codex and blah, blah blah: I had three different GK armies that I fielded previously; two of them are now illegal and one is completely untenable. So yes, I am a little bit bitter about the things they did to the codex, just like how they screwed over Sisters of Battle with their new book by essentially pulling all of the options and flavor out.
With that out of the way, it's not wholly doom and gloom- there's a few neat tricks in here and there are at least some builds that appear to be functional, although just how good they are is still up in the air. But the book at least has some kind of niche, which is more than a few others can say right now.
Combat Squads, Preferred Enemy (Daemons), and The Aegis are still the same and still pretty universal across (non-vehicle) units. Psychic Pilot, however, is gone and dead.
The Grey Knight unique detachment is easily the best thing about the codex- it's 1-2 HQs, 0-4 Elites, 1-4 Troops, 0-3 Fast Attack, and 0-2 Heavy Support; a neat little twist that lets you take more fancy guys. Like all of the other ones, it lets you reroll your warlord trait as long as you roll on the GK table (yawn) and lets Deep Striking begin rolling for arrival on the first turn of the game. Holy shit! Also you can shoot + run (in either order) when you arrive, so you're essentially guaranteed to come down where you want to and to come in with most of your stuff (presuming you use a Comms Relay or other reserve enhancement.) The ability to do a Drop Pod-style alpha strike is amazing and essentially the entire codex lives on this bonus; you can assume anytime during this article I talk about the relative worth of units, I'm assuming the use of this special detachment when I do so.
The warlord traits are a lot less impressive- Hatred (Daemons) and improved casting of Banishment; Hammer of Wrath for the warlord and unit; Stubborn within 12″ of the warlord; automatic arrival and reroll scatter when DSing the warlord's unit; Counterattack for the warlord's unit; and one extra Sanctic power (hilarious with the relic that does the same- know five powers plus the Primaris!) Given how good Command and Strategic can be, I don't see this getting used much at all.
Melee weapons are now the same cost for everyone (unless you start with an “upgraded” one, like the Librarian.) Swords are the default and just have the basic AP3, Force, and Daemonbane (reroll misses and wounds against Daemons when Force is active.) Halberds are 2pts and are +1Str AP3. Falchions are 4pts and are +1A AP3. Warding Stave is 5pts and +2Str AP4 and Adamantium Will. Daemonhammer is 10pts and identical to before.
Special weapons are likewise flat costs across all similar units, with Incinerators being 5/10, Psilencers being 10/15, and Psycannons 15/20 (for power armor and Terminator armor respectively.) Psycannons, as expected, are Salvo 2/4, which is a HUGE downgrade from their previous statline- shooting at 12″ on the move is pretty balls. Psilencers gained the Force rule, which is neat and kinda unique but not actually all that useful 95% of the time. Incinerators are kinda bizarrely expensive for Terminators, since they are the only gun that doesn't benefit from Relentless, but it is what it is I suppose.
Psyk-Out Grenades deserve special note; while Mindstrike Missiles are gone, Psyk-Out Grenades take their place. They are functionally Defensive Grenades when charged by psykers and if thrown during shooting, they act as S2 Frag Grenades that cause a single Perils check on one psyker in the unit (if there are any.) The other kooky grenades are gone over to the Inquisition codex exclusively now.
The relics are mostly kinda meh, but they aren't bad and they tend to be on the cheap side. Bone Shard of Solor is 10pts and gives you a 3++ if there's Daemons nearby, improving to 2++ and Hatred against Khorne. Fury of Deimos is a Storm Bolter with more range, an extra shot, Precision, and Master-Crafted, but for 10pts that's not actually a huge improvement. Cuirass of Sacrifice is Terminator armor with IWND and FNP built in, and at 15pts it's quite affordable. The Soul Glaive is a Halberd that lets you reroll failed tests to cast Force and rerolls all hits, wounds, and penetrations while it is active. Domina Liber Daemonica gives you one extra Sanctic power and lets anyone within 6″ reroll 1s when casting Daemonology powers- at 25pts, not an awful deal.
The HQ slot easily blows away any other for total number of choices, although that's as much because of the slimness of the codex as anything; Brother-Captains are now essentially identical to SM Captains (but with ML1 and Terminator Armor for 150pts.) Grand Masters are 35pts extra for +1A, and +1ML, so not a terribly impressive deal in either case now that they have no unique abilities. The Librarian goes down to 110pts and is otherwise the same as before, but no longer plays a Special Unique Snowflake game for generating his powers; he can bump up to ML3 for 25pts extra. Interestingly, the Librarian can get a Combi-Weapon when virtually no one else can. Techmarines work as they do in other codices, coming as a “bonus” unit for 90pts- they can't get Orbital Strike Relays anymore, but can still get the Conversion Beamer. Brotherhood Champions finally picked up that second wound they've always wanted and their stances now give either Smash or reroll failed saves while in a challenge. They lost Zealot and their special sword (although theirs is master-crafted), and Heroic Sacrifice just lets them make a free swing when they die.
For the named characters, Stern is pretty identical except that he has fixed powers (Hammerhand, Sanctuary, Banishment) and when he does Banishment, it hits all Daemons within 12″ of him. He gets Stubborn as a fixed warlord trait as well. Crowe is ML2 and has all the Purifier powers, but his sword is still derpy. He gets Hammer of Wrath as a fixed warlord trait and can use both stances while in a challenge. Draigo is 30pts cheaper and his sword is S8 AP2 now, but he also has Hatred (Daemons) as a fixed trait and knows Gate of Infinity and Purge Soul as powers above and beyond the usual; that's actually pretty fancy as a trick, although his failure to fill the HQ slot (he's a Lord of War) is actually a huge problem given his cost.
Strike Squads, with the above amendments to cost on weapons and such, are 10pts more expensive but otherwise identical. Given that Psycannons got significantly worse, this leaves them without a really good role in most armies, although the possibility exists for some kind of mechanized force using Rhinos and Combat Squad shenanigans to play the Objective Secured game (this being the only time you wouldn't take their special detachment.) On the whole, though, I don't think GKSS impress much in the new book, as you can't get that mass of S5 shots to bring down light tanks anymore and Terminators do essentially everything they do at a better price point.
Speaking of which, Grey Knight Terminators: they don't suck. Finally. At 33pts per model they actually compare rather well with a lot of things and Relentless means a lot with the way GK's special weapons work now. Although you have to pay for melee weapons now, which may mean a lot of remodeling for some folks, they are solid hitters even without any combat upgrades and with Hammerhand up they will butcher most units pretty badly, even MCs and even Dreadnoughts in a pinch. I think these are the go-to Troop option (at least insomuch as you need that singular Troop squad) with the new book.
Paladins are an interesting comparison to Terminators- with the same price as before and the same statline, they come out of things looking fairly okay, though Solodins are a thing of the past. However, you still get two Psycannons in a 5man squad and the Apothecary is just a 20pt upgrade rather than the insane price it was previously. If you aren't expecting to see a lot of S8+ shots, they can be a very strong choice to throw in someone's face.
Purifiers still do what they do, although an increase to ML2 and keeping Cleansing Flame can both be regarded as major boons. Probably a good complement for the “in Rhinos” army, but less so for the teleporting one.
Dreadnoughts got moved over to Elites and are the only psyker vehicles in the codex. (I guess everyone in a tank just forgot how to cast spells.) However, at 125pts- and 25 more for the Venerable- they are pretty intensely overpriced, especially since they don't even come with a Force Weapon of any kind. Don't expect to be seeing any of these around anytime soon.
Rhinos are exactly as they are in every other book, which ends up being alright. Razorbacks are, too, which ends up being garbage. 55pts is not a good price for one Heavy Bolter, sorry.
Interceptors are slightly cheaper per model (2pts) but are the same base price because of the sergeant tax. They benefit a lot from cheaper Incinerators, but the loss of Psybolt hurts them quite a bit, so it's probably a wash.
The GK Stormraven has been brought in line with the others in all respects now. It's your only source of AA, but since you don't have a good reason to transport a Dread and can't get Psybolt, there's no a strong reason to take it.
Purgators also get hit with the sergeant tax; changes to weapon prices are a bit less clearly beneficial or detrimental to them.
Teleporting in five of them with four Incinerators can be pretty hilarious against enemy infantry, but since they fight for space with the Dreadknight that may be a bit much to ask of them.
The Dreadknight itself is quite a beast; Personal Teleporter is a ton cheaper, but with the ability to DS it in turn 1 that may not be needed so much anymore. All of the weapons got cheaper and most of them got better as well- the Heavy Psycannon can fire on Salvo 3/6 mode and the Psilencer gets force just like its smaller cousin. Its stock loadout is just two Power Fists now (with 5pts to grab Force/Concussive with a Daemonhammer or 10pts for Force/MCed with a Greatsword), but the real gem here is its psychic powers- Sanctuary and Banishment means it can get a consistent 4++ in addition to T6 and 2+. Drop in, blast some infantry to pieces, and then go for some big assaults- the Dreadknight is no joke.
The Land Raider and its brethren are the same, minus Psychic Pilot and the small cost bump that came with it. No real reason to pay a ton of points for them when you can just teleport in for free.
Hmm. Well, the unit selections are crap- you have one, maybe two units even available in most slots, so your useable pile is even smaller. And your options across different units are very same-y; the entire book is basically S4 and S7 shooting and S6 melee now. So mechanically, it's an amazingly bland book that I doubt is going to hold up well under the press of time. However, the ability to cram a bunch of Terminator-quality models into an alpha strike is pretty significant, so it may have some competitive legs under it.
All in all, though, I'm extremely disappointed with the half-assed job GW did here. A lot of people aren't happy with the Ork or SW codices, and perhaps that's fair- their is a certain lack of je ne sais quoi about them, especially when it comes to the fluff and picture sections. But the Grey Knights codex takes this leaps and bounds further, pulling almost all of the interesting parts of an already-borderline codex and giving them almost nothing in return. If this is the direction they are taking the game, I am not impressed or enthused.