Wow! Talk about an embarassment of riches! Everyone's saying such nice things!
To answer a few questions, and respond:
First off -- to Nightfall, Morrus and others -- thanks so much for the warm embrace of the book. I've been working on it in one form or another for about 10 years (and writing for the last year), so it's very rewarding to hear people are enjoying it; especially people who weren't interested in it (ala Morrus) or who are absolutely sold on other settings/cosmologies (ala Nightfall).
Gothmog -- yes, I agree wholeheartedly that the Holy Warrior could be tremendously useful for Neutrals and Evils. Here's why I didn't write it that way: the Gift of God could (perhaps even should) be, in my opinion, something else for those alignments. For instance, a lot of people are quite fond of the fact that the Blackguard gets sneak attack where a paladin gets cure disease. I haven't decided, but I think maybe an Unholy Warrior class (evil only) would have some personal abilities like sneak attack every few levels rather than the spell-like abilities Holy Warriors gain. For some reason, I also feel strongly that a neutral version should have something instead of the steed/animal companion and definitely shouldn't have turn or rebuke undead. I couldn't at this time say why I feel strongly about it, but I do.

Point is, I think there can be significant differences between the good warrior set out in BotR and neutral and evil versions. Those differences bear some thinking. I wanted to do that thinking rather than provide an attempted "catch all" class in BotR, which was (after all) focused on ostensibly good gods. On top of that, the class is already a complex one based on variables (you get four powers of power-level x at 1st level and two of power-level y at 2nd, etc.); I think having to also write text explaining that the turn undead ability is rebuke undead if you're evil, would just add to the confusion potential.
Nevertheless, all that being said (and said with my usual uneconomical use of words!), I think it should be pretty easy for enterprising GMs the world over to create an evil version of the Holy Warrior before I get around to it. I look forward to seeing the ways it's done!
As for the celestial servants of each of the gods, that's what Tree of Life is for. More, Chris has announced an upcoming celestial-themed book. While all Green Ronin products of this sort maintain a "stand alone" status (it's annoying to have to own a $100 library of a company's products for the book you just bought to be useful and, as ListLurker observes, Green Ronin loves you), I bet Chris will have some compatibility with BotR built in.
And I reckon the 3rd fiends book will have a few happy surprises for folks who now know the BotR cosmology. I worked extensively with Chris on all the mentions of Gehenna in BotR. He and I were both unhappy with the existing bland representations of the NE realm as "a battleground between hell and the abyss populated by mercenaries." That's so dull! I think people will really enjoy what GR is up to for the daemons in book 3.
Anyway, again, thanks! And as always, I'm happy to answer questions.
AJL