I'm probably alone on this one, but Shadowdancer! Always makes me recall some vague memories of really old black and white cartoons, you know, where the person goes one way and the shadow goes another. I like the roguey-shadowy concept, but its execution does nothing for me.
And the abilities seem all wrong too. Shadow companion can kill almost all non-magical beasts, certainly all mooks, all by himself. Shadow jump is neat, but it only starts to get useful at 6th level. At that level you can jump 40 ft, which is the diameter of illumination from one torch sitting in a dungeon corridor. So if there's only one torch in a corridor, with a watchful BBEG at the end, you have a chance to sneak up on him. Never mind that your companions are at least 13th level, where they can go invisible, dimension door, abundant step, etc their way past that torch much more easily than the shadowdancer.