The shadow does start off very easy. I have easily leveled up as a Kinetic Shadow. While it does become more complicated as you get to the endgame, you also have to account for the fact that you've had the first 40 some-odd levels as a learning curve. But the time you get up in levels, you'll most likely have a good idea of how to use your spec. From there, you can just tweak to increase effectiveness and efficiency.
So in short, yes, the shadow is complicated, but only if you inherit a 50 shadow. If you level him up, he's very forgiving in the beginning and would have learned a lot of how to use him properly by the time he starts becoming complicated.