The film seems to have either very positive or very negative opinions, people find it hard to be stuck inbetween. I appreciated it for being a heist movie with an emotional depth but also a study into the world of dreams - and the bit at the end of the movie, literally the last few seconds that you will see Mustafa, i think perfectly somes up the idea behind the movie, you're not sure what is reality and what isn't. The end is also a twist because there is a theory that...
Spoiler for : (hover to see)
The possible theory caused by the ending (although i think there are facts that disprove it) is that his wife was right all along - and that when she died she really did wake up and the entire movie is still Cobb in a dream world, so everything that happened didn't really happen and was all in his mind. There's alot of little tips to this throughout but i can't be bothered to go through them all. However i don't really think that's what you're meant to believe - i think the fact that they talked about the 'totem' poles means cobb was awake and the thing with his wife isn't that much of an important aspect of the movie - I see it as just a character development sub-plot that you're not meant to focus on too much. The ending is just whether or not he managed to wake up from going to look for the Japanese guy or not... but it's up to you.
It's kind of hard for me to explain everything here and i'm not sure it would make any sense what i believe because the movie is complicated, so ill just say that i really enjoyed it, and i think the movie production was top notch. None of the stunts were stunt-doubles, none of the spectacular effects (like the rooms spinning around and the rooms tipping sideways) were done by CGI but were all done by clever construction works and the characters having to sometimes grip onto parts of the set secretly to stop themselves falling over. The writing is fantastic as it is with all Christopher Nolan films, and the main thing is it gets you talking. I think in the low character depth (besides Cobb) and the way in which the plot unfolds too quickly, it definitly has weak points that not everyone will like, but overall i'd give it a 9/10.