Inception.
First of all, Inception is a must see and is a must see again! It’s a complete mind fuck on so many levels (pun intended—if you seen this movie you’ll understand). The movie is visually stunning and creative. It’s everything you want in a movie. The story line is so rich and in-depth that everyone can walk away with their own ideas on how the movie ends.
IF YOU DIDN’T SEE THE MOVIE DON’T READ ON!! SPOILER ALERT!!
In my opinion, Cobb wakes up and the ending is happy. I believe this because Cobb was told something along the lines of “use your ears, not your eyes” by the Asian guy that hired them. I believe I heard the top topple immediately after the screen turned black, hence believe what you hear not what you see. Also, every time he spin the top in a dream state, it never wobbled. Being that it wobbled in the end offers proof (to my theory) that it did fall. Plus he finally gets to see his kids’ faces. He could never see it before because he didn’t have the memory of it. My last reason is based off of how Cobb kept asking Adrianne and Fisher how they got to where they are and that in dreams you can’t re all how it started. However, in the end we see Cobb go through customs, meet up with his father-in-law and see him go home. I believe if it were a dream it would’ve just showed Cobb home with his kids.
That’s my take on the movie but I came across a lot of theories. Here’s a link to a really cool theory.
http://halphillips.tumblr.com/post/822919795/inception
Enjoy.