I walked into the theater with a thought that this movie is so much very great. It turns out that it is just a so so movie. Acting skills: no room to act.
Originality: yes, to me, the idea of stealing or inserting an idea from/into ohe’s mind during his/her dream is novel. (unless I’m not aware of this). However, several pieces in the movies are not original. For example, in the dream, you have a box of city (city can be fold) or a stair with illusion. Many ideas are exactly followed from the basic psychology.
Complicated: not at all. The idea of several layers of dreams is easy to follow. Not many twists. The conversation have no thought. In my dream, I would have a freedom to imagine, to dream. Here, the dreams have many rules to follow. You are boxed.
Of course, if you just want to entertain, then it’s worth your time. But don’t expect too much. If I have to choose between Avatar and Inception, I would choose the first one.