An alternate take on the Pathfinder drow, but one that is close enough the standard concept for parts of it to be easily used in campaigns not set in the world of Aventyr.
The book begins with the mythology of the Underdark and its creation. Although this does not deal heavily with the drow themselves, it is well written, and provides an interesting context to the race. This is likely useful stuff if you're using Aventyr (as is the idea), but it's the latter parts of the book that are likely to be most useful to those who are not.
Drow society is not described in depth, although there are the standard guidelines about alignment, adventurer origins, and so on for those playing drow as PCs. There are also traits modifying skills for male and female drow, to keep the two genders distinct, as well as bonuses for characters with particular favoured classes.
Almost half the book, however, is taken up with new rules for equipment, feats, magic items, and domain spells for use by drow. Although referred to, naturally enough, as a drow domain, the theme of the spells is, more generally, that of shadow and the shadow planes, and could therefore potentially be used by other races if they worship the right kind of deity.
On the whole, a good book, with some nice ideas for using the drow, and well-written with good artwork and layout.
[4 of 5 Stars!]