Inception is an ambitious movie. Packed in a sci-fi heist movie are discussions on the nature of reality and fantasy, guilt and regret, family, nihilism, loneliness and there is probably an analogy to the gold standard or the War of The Roses if you look hard enough. In other words, watching this movie is like having an entire freshman year's worth of discussions with the stoner down the hall. That's a lot of material, and probably explains why the movie is about 20 minutes too long,
The movie stars that kid from a couple episodes of Growing Pains, who is on a quest to discover if the color blue to him is the same as the color blue to you. Joining him on this odyssey are The Scarecrow, a samurai, that kid from 3rd Rock From the Sun and a green screen. When the movie sticks to its basic plot, it's a lot of fun. The action scenes are all well done. The movie takes its time building the tension, and it pays off nicely with an intricate but intense finale.
The movie loses its luster when we take long detours into the protagonist's past. We are forced to sit patiently while Leo explains to us, through pouting, that he is sad. The frustrating part is that it's completely unnecessary, and even hurts the film. The movie clearly has no problem letting the audience puzzle things out for themselves, so why club us over the head with this? Why no just drop casual hints along the way, and then when the big reveal comes at the end, it's actually a powerful and satisfying revelation.
Finally, there is one thing I want to address by not addressing it. Whenever I hear the movie being discussed, it always devolves into an argument about what was a dream, and what was real. The only answer is that we can't know. For all we know, the entire movie was the dream of a 9 year old Martian vampire living in the year 4000. So just relax, enjoy the movie, and ask yourself the only really important question, "Will this sync up with Dark Side of the Moon?"