It was good! Which hasn't happened in a long, looong time. (Last good movie I saw in a theater was Up, to give you an indication.) Inception is all about dreamworlds, which usually is the sort of thing I don't enjoy that much. The surreal creeps me out. It's very easy to tip the balance from enjoyably edgy and weird to disturbingly edgy and weird. (Difference between dream and nightmare?)
I think three (non-spoilery!) things went a long way towards keeping the balance on the right side for me.
For one, Nolan told an honest story. He didn't use his conception as an excuse to do multiple fake-outs just for the sake of trickery. He was disciplined and I appreciated that.
Second, logic still applied. Which isn't something movies dealing with dreams tend to do. Relying on my memories, it seems to me most dream-movies tend to take the surreal of the dream-world and paint it across the "real" world and you're locked in this house of mirrors where nothing has sense. But in Inception, you still had this frisson of "wait, is this real?" because a certain amount of logic still applied. I really, really liked this way of doing things.
Third, Ellen Page. She's just so solid. So having her there, either asking questions or giving explanations or otherwise reacting to what's going on around her, gave things a real-world weight, dream or no. I thought the casting pretty awesome all the way around, but Page was a stroke of brilliance. IMO. :)
In conclusion: I recommend Inception if you're in a movie-watching mood.