I got the book in the mail yesterday, and I read half of it before bed last night, kind of skimming over the advances and other highly crunchy parts.
What I liked:
Influence seems to rock. It also supports my old flamebait idea that an inquisitor tends not to equip his acolyte cell, as mechanically, not only do the acolytes cost perm-influence now to create, but you can lose influence if you equip your cell too frequently, or even generate enemies if you requisition equipment that the cell doesn't return.
The concept of 1 inquisitor with a cadre of throne agents. Much better than everyone getting their own rosette and bucking the trend of lone wolf Inquisitors
Most of the Ascended classes are, fluff at least, kind of interesting. There's not a lot of choice per se, but they generally feel pretty good.
Fettering your psy powers. Sweet. Pushing is cool too.
A general idea of WTF the Inquisitor is doing. Knowing where the Acolytes end up helps me as a GM shape where they have yet to go.
What I'm meh on:
Master Skill groups. I understand the idea behind them, but they just seem... meh... to me.
Some of the crunchy bits feel underwhelming.
The talents/abilities either seem rather BS or anemic, but then again this is an "epic" campaign setting.
Ascension paths. There aren't enough of them simply put. They're a great concept, but they seem like they needed 3-4 options per career instead of 1-2.
Creating an ascended from scratch is roughly akin to ripping out toenails. I understand there's no easy way to do that, and the top-down approach seems pretty decent, but crikey that's a slow build for a character. I guess this is a problem more with the advancement system in general (a rank 8 character that gets killed and is created anew isn't going to be fun to stat either) than with the book.
However, it got me interested as a whole in my DH game again. My players are eager to start again, and with some idea of the politics and backstabbing in the game, I can get a good grip on new storylines that play out between inquisitors, with the PCs as acolytes stuck in the trenches.
Moreso, Deathwatch coming out in August has given me even more interest in the story I'm telling. Once the PCs ascend, they will have tasked to them a small squad of Asteres for their overarching mission. When the story needs to be shaken up, or the story narrative goes to a particularly dangerous place, I can shift the players over to their Deathwatch characters and feel somewhat better about sending them in against insane odds. It will keep my players interested in the story, switching between whack-bonk and roleplay, and it will allow me to explore different themes while still tackling the overall plot.
All in all, it was a good investment. We'll see how playable it is when we get there though.