This is a great book and the only reasons I'm not giving it five stars are:
(i) the fact that it could have used more maps; and
(ii) the fact that it ignores the Naacal people, their enslavement of the Lemurians, and them being the ancestors of the Stygians:
For those of you guys that aren't really into the setting, the Naacal were a people inhabiting the east of the Thurian continente during and after the last cataclysm. After the destruction of Lemuria its survivors were enslaved by the Naacal, and then they migrated east. Hyrkanians are the descendants of the Lemurians. Now, the Naacal also migrated, and after intermigling with some (human or inhuman) Stygian race they became the current Stygians. Other sourcebooks deal with this history.
Wanderer not only states that part of the Lemurians became the Stygians, but fails to identify the Naacal as those who enslaved the Lemurians. Instead the book states the Lemurians were enslaved by an "inhuman culture" (check p. 37 for both references). This contradiction reveals an unfortunate lack of consistency.
[4 of 5 Stars!]