If there's one thing that fantasy gaming has always needed, it would be more products that focus on the little details of a given culture. Books like Martial Cultures: The Sijara fill that particular need quite well.
As a GM who enjoys having varied cultures that go beyond simple stereotypes, I found Martial Cultures: The Sijara to be an entertaining read that goes into detail about the nature of the Culture in question, from their beliefs, their myths, little details like fashion options and the idiosyncrasies that make characters of that culture to be more than just another face in the crowd.
What I liked the most about this book is how easily the author enables players to understand the Sijaran culture and makes it easy for them to play one without having to go too technical. Little details like fashion choices and little behaviors that may seem just a little odd to outsiders are explained in a fashion that makes sense in the context of a "real" culture and that alone makes it a great read.
For those interested in crunch, the book also goes into full detail on how to integrate the culture into a campaign setting, adding little rules tweaks, sample feats, character options, and even plot hooks.
Overall, Martial Cultures: The Sijara is a dense, well-written, and interesting book that lends much-needed flavor to the standard fantasy rpg campaigns out there. I'd definitely recommend it for GMs or even players who are looking to lend more depth to their settings.