This movie is phenomenal. A total mind trip. Chris Nolan is my favorite director. Memento and Inception are stellar examples of how Nolan is a master of cinema. They're not just good movies, they're good for movies as an art form. He reveals the uniqueness and value of the motion picture medium by creating stories that no other medium could tell. For that reason, Inception is more of an experience than a movie.
Super-brief summation: it's about people entering others' dreams. There's surprising little else to say about the plot. It's similar to The Matrix in notable ways: the difficulty in explaining the plot without it sounding flat or even silly; the philosophical examinations of reality; non-stop action yet interesting characters and relationships; the ground-breaking effects that redefine what's possible; and the exhilaration that lingers longs past the credits. (Oh, and they are also currently rated the same on Rotten Tomatoes: 86%.)
There are layers upon layers of excitement and drama right up until the very last frame. So yeah, I kind of liked it.