Angelology is rather like a more intellectual and literary Dan Brown novel. (I mean that in a good way, honest.) Unlike Dan Brown, Trussoni is actually a decent writer and does her research, but I still found the story a little too absurd to really cut it as a great fantasy novel. I'd actually give it 3.5 stars, so it gets rounded to 4 'cause I'm nice that way.
This book has all the virtues and flaws of a "literary" author taking on the fantasy genre: it avoids a lot of the cliches you usually see in contemporary fantasy, so it's a fresh approach to the "secret society fighting a covert war against the supernatural." On the other hand, while the writing is beautiful and the characters are well-drawn (and definitely not your typical heroes and heroines -- most of them are elderly academics and nuns!), there are some gaping plot holes, and at times the action scenes had me saying, "Oh,
come on!" Trussoni's sense of timing seems calibrated more for a big-screen treatment than plausibility.
Also, pages and pages of infodumps, and dialogue that is indistinguishable from the main text.
Everyone talks exactly the way the author writes.
If you like Dan Brown, this is a cut or two above. If you like supernatural thrillers, books about angels, etc., then give this a try. If you're a contemporary/urban fantasy junkie, then this might be a diverting change of pace, but it may or may not be your cup of tea.