First things first, the book is lavishly illustrated, full colors and realized with excellent materials, from glossy paper to a very strong hardbound cover.
The section on Gnomes finally explains why the pointy-hatted little burrowers are so often depicted as smiling.
They won't let you make Muls, but you can make half-giants, so Darksun is only fifty percent told to go find somewhere else to fuck.
EDIT: Actually, if you got the numbers right you could probably run it as a skill challenge.
Due to its strong emphasis on fantasy, the book shows all the possible relationships between adult members of the various races: human, elf, orc, dwarf and others, including what happens when the partner is "not so human" god, demigod, dragon, fairy, demon or devilkin and so on.
It is in no way sexual, but was included mostly for the purposes of them being able to add "oh, and uh, spells and stuff can't quicken the process of healing the penalties, except of course for our other Prestige Class, the Sacred Prostitute.