Well, it's been a long seven years of waiting, but after having had my brand spanking new Codex: Tau Empire for a week now, I'm ready to put some thoughts down for posterity.
First off, man is it good to have some real fluff! The previous codex was basically just a cut-and-paste job from the first one, actually managing to lose more than it gained, so to see fully a third of this 104-page hardcover devoted to nothing more or less than the background of the Tau Empire in general, and the Fire caste in particular, was lovely. We have individual unit entries again, like a real army book!
The quality of the fluff is likewise pleasantly high. It really feels like Jeremy Vetock sat down and thought about just what it would mean for a race in 40K to try and run a unified polity without meaningful warp travel. The introduction of cryo chambers as being fairly standard issue for long-range spacecraft, and the Tau's tendency to freeze particularly promising commanders so they can be called on in times of greatest need, also goes a long way towards dealing with some of the weird chronology issues that cropped up in the second book. No longer do we need to try and figure out how Shadowsun could've been a contemporary of Farsight before the Damocles Gulf Crusade, and still be around to lead the Third Sphere Expansion! Or how Aun'Va could live long enough to go from battlefield to battlefield given the Tau's slow starcraft! It's a nice little way out of the problem, and a unique one in the setting, giving the Tau yet another little detail to set them apart from the other races of the forty-first millennium. The background stuff also gives those little tantalizing hints of the wider world that 40K is so good at; there's reference to a host of other alien species subsumed by the Tau, including their first contact, a race that was dead just a few generations after joining up. The book doesn't say the Tau wiped them out, either purposefully or accidentally, but it's ambiguous enough that, well, you can't quite help but wonder...
The one thing I didn't like, though, was the slight de-Tau-ification of the actual writing in the codex. For instance, it's not Shas'El or Shas'O anymore, it's Commander. Also, what the heck happened to the Shas'Els? Are they piloting the tanks now, is that why they have BS4? The rank just sort of disappeared. It's a little thing, I fully admit, but what is life but a cluster of little things?
As for the codex as an army book for a tabletop wargame, while I have some misgivings they in no way overshadow how genuinely happy I am with what Vetock did with the army. Yes, it sucks that we lost vehicle multitrackers and targeting arrays and the advanced stabilization system, but you can't say he didn't try and balance that out with a combination of changes to existing units and giving us new toys to play with. The basic XV8 got cheaper and more versatile, with built-in multitracker and blacksun filter; Fire Warriors got slightly cheaper; Pathfinders got slightly cheaper and no longer need to pay the Devilfish tax; the railgun-armed Hammerhead got way cheaper (though the IonHead is basically a wash); the SDT is actually worth thinking about; plasma rifles got cheaper, and fusion blasters got longer ranged, and the burst cannon and pulse carbine picked up an extra shot, and then there's the Commander... good heavens, the Commander. Tau finally have an HQ unit that's worthy of standing up alongside those of other codexes! Which is amusing, because at the same time the book introduced a bunch of new HQ units to go along with it; it never rains but it pours.
I'm working on a more in-depth review of the units and wargear, but in the meantime I just wanted to say that the new book is excellent. As a fluffbunny, it offers me exactly what I've been waiting for, and what I manifestly did not get last time around. And as a tournament player, it offers me a solid army that I can kit out in a wide variety of equally playable ways. It's not perfect, but since nothing in life is, that's a silly standard to hold it to. It is, however, about as good as could reasonably have been hoped, without being made so good that other players are likely to resent it as being broken. Vetock delivers the best the fanbase, both Tau players and non-Tau players, could have asked for with this book.