I'm a bit surprised I'm only the third person who didn't think the film was all that great.
After reading in this thread about it, I was quite hyped, because it's exactly the kind of story I tend to enjoy: Mixing reality and illusion/dream/hallucinations. I'm also a big fan of Philip K. Dick for that reason.
However, imho, the movie fell flat. I felt it was a missed opportunity, given how the premise seemed so intriguing.
The story at it's core is actually quite simple. It's artifically complicated by stuff that doesn't really add much to it.
I was also disappointed about the lack of 'proper' dream logic in the movie. To me the dream sequences weren't dream-like at all, it was just a bunch of different sets. Take the inception mission: What are the dream layers really about?
We get city blocks, a factory hall, a hotel, a fortress, and the 'dream-world' city. But the only thing that is different is the locations. They could be replaced with anything else without affecting the plot/story in the least.
The special effects were okay, but the action scenes mostly seemed kind of pointless. I also felt that I didn't really care about the protagonists. The explanations why it was supposed to be dangerous to be wounded/killed in the dreams also seemed wobbly and unconvincing to me.
It was too obviously intended to just serve as a device to convince the viewer that there's actual danger involved in getting into other people's dreams.
Imho, Matrix and 13th Floor did a way better job at telling a very similar story. Inception didn't really add anything exciting or new to this particular sub-(sub)genre.
There, now go ahead and rip me apart for not seeing the brilliancy of this movie
