First of all, I like the movie. The story is catching, which reminds me of the works of Hitchcock. If we describe a movie as a building, then there is no structural problem. Every part is closely related and presented in an elegant way.
But there is one thing I feel unsatisfied, probably just my personal taste. Like the dream it discusses, the movie lacks details. Not the plot details I am talking about, but some delicacy I feel missing. I refer to another two my favorite movies, Godfather and Seven Samurai. These are two movies I can appreciate every day. There are always some delicacies that I can amplify and enjoy. However, I do not have the feeling that I should watch Inception for a second time. Still using the building analog, Inception is like a modern skyscraper. Magnificent, fully functional, but not enjoyable. Maybe I shouldn't complain too much, and this is just Nolan style.
A serious and nice movie, anyway.