I run my groups' adventures in a homebrew world, so usually I'm not too interested in setting books. This setting, however, has so much that feels different from a generic 'medieval Europe' fantasy setting, that it immediately caught my attention - and most of this setting I can 'transplant' to my own world right away.
Two things from the book that I like most are the Calashite Mosaics magic items, and the Adventure seeds. These Seeds are short descriptions of adventures that you could run, stand-alone, or as a larger campaign. They gave me a lot of inspiration for possible future adventures in my version of Calimshan!