The one thing I liked about this book was it was quite easy to find what you were looking for. Hence the A to Z bit in the title. Also, I adored the fact they showed you the sources used under each section and in the back so I could look further in my research.
Yes, this book did hold a lot of information, but I felt like half of it was unnecessary such as popular people who wrote about angels or learning about angel stamps. Sorry, but why do I care about Billy Graham? I want to know more about the angels themselves and some of the stories about them, even classic literary pieces like Paradise Lost. I'd rather not have to skip half the book for crap like Angel Times or whatnot.
Besides the overload of useless information, it wasn't terribly bad. As stated, it did make it easy to find your section, but considering it is a dictionary, it should have been. A lot of the information was repeated, but that is only irritating when you plan on reading the entire book like I did. I enjoyed the fact that they brought in other religions like Zoroastrianism and Islam, though I wish they had more on the former. It definitely peaked my interest.
Another thing I disliked was all the faeries in here. I know the fey are considered angels of sorts by the Irish and Scottish, but no one in the book did it explain that. It never explained why all the faerie types were in there like the brownies, trolls, etc. I do have a slight interest in the fey realm, but I don't think they should be in the ANGEL book.
I also would have liked to have seen more information on the fallen angels. They had a decent amount (for a dictionary) on the fallen Grigori, but even most of that was on repeat. Would have definitely liked to have seen more of Lucifer/Satan. There are a lot of different versions/theories on him, and they pretty much only shared one.
In short, half the book held decent information. The other half is utter crap or has almost nothing to do with the subject, but at least it is easy to find things in.