This is the supplement I've been waiting for. Everyone who I've played Rogue Trader with has skirted Imperial rule at best and obviously flown in the face of it at worst. Now, they finally have the ability to take alternate career ranks in just the type of criminal they have always wanted to be. More than that, the book describes what exactly a Rogue Trader should be expected to get away with and what would get them all but killed in the more "civil" parts of the Imperium. There are a number of adversaries for the players to contend with focused on Imperial lawkeepers, Inquisitors, and the like. Take that to the next level and you get the Nemesis path. This let's the GM create a fully fleshed out nemesis for his RT crew. It's a nice addition with some RP elements to make them feel more real. Finally, you get a ton of exotic and ridiculously valuable loot that your players can pursue. They obviously require a bit of smuggling and probably some treason to really take full advantage of, but you can't make an omelet without overthrowing a few Imperial planets.
I love the Warhammer 40K books and this finally gave me the kick in the pants to get a campaign going AND convinced my gaming group to jump on board to be flagrant space pirates. The art is insane as usual, so there's no reason not to buy this book.