Relentlessly ambitious, Nolan aimed to introduce a degree of intelligence to a genre that otherwise relies on big-budgets, spectacle and an over-indulgence of an outdated masculine ideology.
This is not to say that 'Inception' fails to offer a spectacle, a number of scenes in the film gleefully showcase the capabilities of modern technology. Thankfully, though, Nolan was more interested in creating an intellectually stimulating narrative - one in which you cannot simply switch off and passively absorb.
'Inception' is not 'simply' another heist movie, it is not 'simply' anything. It is a complex organism that possesses it's own internal logic; it does not strive to adhere to what is universally acknowledged as reality.
Engrossing, innovative and utterly captivating, 'Inception' is certainly an anomaly in an otherwise predictable genre. To say it is simply a "film about dreaming" is abhorrently incorrect - and somewhat insulting. It could be argued that this is a film about the nature of cinema itself, or perhaps one that compares cinema to the nature of dreams.
My evidence to back such a claim: would anyone care to explain how Cobb found himself on the beach at the beginning of the movie?