Let's start with a few points that probably made the movie one of the biggest hit of the year so far;
The secrecy of the story. The trailers gave away very little, only preparing the audience for a roller-coaster ride, which it delivered.
The story itself was well thought of, different, unique and kudos to Christopher Nolan for coming up with it.
I believe since Nolan came up with the story it was the icing on the cake that he himself went ahead directing it. The movie is executed very well.
The cast was perfect. Leonardo DeCaprio, Ellen Page, Joseph Gordon-Levitt, Ken Watanabi along with so many others is a perfect mix.
The movie is visually brilliant. Cities folding and collapsing, never ending staircases and excellent car/people chases. The special effects are top-notch.
The Psych Element. Everyone is always fascinated by the human mind and how it functions. It’s something personal and a story based inside dreams and one that talks about the subconscious is very likely to interest people.