I'm not going bother with a real review, and I'm assuming if you're reading this then you've already seen it. If you don't want it spoiled, bugger off.
Coming out of the theatre, there seemed to be two main theories among the audience as to what had happened in the movie:
1) Cobb's mission planting an idea in Fischer's head was successful, and he also successfully rescued Saito, and he was re-united with his children at the end.
This is of course nonsense. The top keeps spinning. He's still in a dream.
2) Cobb's mission planting an idea in Fischer's head was successful, but he didn't escape from limbo, instead dreaming he was reunited with his children.
This is the theory most of the smart people seemed to be leaning towards. It explains the too-pat happy ending, the fact that his children don't seem to have aged a day from his memory of his last look at them, and the top still spinning away on the table when the movie ends and the screen cuts to black.
It's also just as wrong.
Let's go back to basics for a second. Inception is about Cobb, a former architect, who now makes his living extracting ideas from people's heads by constructing shared dream scenarios and placing his targets into them. As the film progresses we learn some of the rules, including the fact if you drop too many levels down into dreams, you get dumped into a limbo of the unreconstructed subconscious from which no one has ever escaped with their sanity intact (except, apparently, Cobb.)
We also learn that when you are in a target's mind, they will create projections as defense mechanisms that attack you and try to drive you out.
You getting it yet? No? Then we'll continue.
During the set-up for the mission to incept (plant an idea, rather than extract one) Fischer, Cobb spends a good chunk of time running around like he's James Bond, dodging the assassins sent by a disgruntled former employer. In fact, we never even find out the identity of this former employer - they and their goons evaporate once their plot purpose is served.
Hmm. Odd that an architect can pull that off, isn't it? Even Mal (Cobb's dead wife, who keeps re-appearing as a guilt-driven projection to disrupt his missions) comments on how improbable it is, how dream-like it is.
Which, of course, brings up another point. Projections are supposed to be defense mechanisms against intruders. How can projections from Cobb's head - not just Mal, but also things like the train that hits the getaway car and plows through traffic in level 1 of the mission against Fischer - be projections from Cobb's subconscious defending someone else's mind?
They can't, of course. Any more than an architect can dodge trained assassins.
There's plenty of evidence throughout that what's going on is all a dream, that at no time are we in waking reality, and that the dream is Cobb's. The fact that different characters echo each other's dialogue. The absolutely ridiculous way Mal frames Cobb for her suicide and forces him to go on the run, separating him from their kids (you're telling me that no one in this post-CSI world of ours could prove that they were on opposite window ledges when she fell? Puh-leez.) The fact that, just when Cobb needs a new architect, his father happens to be teaching one even more gifted than he was?
Or how about the inconsistencies in Cobb's stories of his and Mal's life together in limbo? They build entire cities from their imagination, they grow old together... yet when he finally plants the idea in her head that it's all a dream and that suicide is their only escape, suddenly they are young again.
But if what happens in the movie is a dream (within a dream within a dream...) of Cobb's, that introduces a few other questions:
1) Is anything we see real, or based in reality?
2) What is the titular inception?
3) Who's doing the inception?
The second question is the easiest. The target of the inception, of course, is Cobb himself.
Before I start spinning my theories on the rest, though, I want to see the film a second time.