This is a great source, it has 19 prestige classes with their respective organization that not only can be applied to the rogue class but also to the ranger and bard classes, their all well balanced, but most importantly you would want to play them all.
It also has 13 legendary classes, this is a great concept, because it will give you more options for high level campaings, and because the tests you would have to take to achive them would give your DM more material for adventures (and this adventures will be very exiting).
The art of the book is also great, some people won't like it because it's black & white, but I think it's perfect for a Book called Path of Shadow.
If you are looking for a great source book with complete information (and that is better than the oficial one) this is it.