Good movie, probably the best this summer has to offer (though that's not saying much) but not the classic that the Nolan fans swear it is. A big issue is that the movie's central plot issues aren't particularly engaging...on the one hand, this is about two corporations slugging it out for global control ("Coke or Pepsi, people...could the stakes be higher?!"), and on the other, about an acknowledged corporate criminal getting to see his kiddies again (giant plot hole there...why didn't he just have someone bring them to Europe?!).
The biggest problem for me was that the movie's approach to dream logic and structure feels too regimented...I never bought the "dream within a dream within a dream" premise. Dreams (as we've all seen) are too loose, too diffuse and ephemeral for that to seem like a realistic approach. What's more, the climax never delivers on the jaw-dropping physics shown earlier, when Ellen Page's architect folds the entire landscape over like origami, though the zero-gee and "limbo city" had their moments and were a welcome respite from the car chase and skiing "levels", which I found annoyingly uninspired. The mistake Nolan made was, while few of us will ever ride in a spaceship or be involved in a sword duel, nearly everyone dreams on a regular basis, so a basis of comparison is pre-established, and it's hard to say he delivered on the plot's lofty premise.
(For a more accurate depiction of dream composition and surrealism, see David Lynch's "Lost Highway", "Mulholland Drive" or especially his most recent, "Inland Empire"...)
As for the big twist ending...as Brendan N said above, one outcome is significant (Cobb is trapped in a limbo he helped create), while the other is almost entirely unengaging ("Yay! A criminal did something illegal and got away with it!"), and the top's wobble pretty much hints that the latter is the case (more evidence for a happy ending here) so...not exactly keeping me up nights wondering.
I second Raoul Duke...it's been done before, and better, but it's not time or money ill-spent...
On the whole, human beings want to be good, but not too good, and not quite all the time.
- George Orwell
By all means let's be open-minded, but not so open-minded that our brains drop out.
- Richard Dawkins