The middle tree (Deception) is the one closer to a WoW Rogue. I second the recommendation to respec and put all your skill points into it until you reach the top.
Check out this guide:
It will give you sample skill tree builds and "rotations", that is, what skill and in which order you should use. It is geared towards level 50 characters, so it will mention a bunch of skills you don't have yet, but it is a good starting point.