It's an original idea to introduce the alternate world of someone's mind as the place of the action, and by this i mean doing voluntary, deterministic, cause and effect actions that do affect the reality of the character involved.

I'm not a great movie fan, i don't really make a goal for myself in following some trend or idea in the movie world, let's just say I feel sometimes the TV set has too much control on the movies I watch, :), and coming from this I dare to say that the theme is not quite present in the past years, and this is a good thing to start with for a success movie. But besides being an original idea, i think it's followers failed to make the most out of it.

My point is that if you try to extract from the movie the specific of this new world they discovered for us you can see it's not too much. You can bend the cityscape, you can make the things explode, there are new specializations for the people involved (some create and some just act), and somehow you can keep some dead people consciousness trapped inside this world, and there's a door to some dark other world where these dead people go. And this is all about this mind world.

The bad thing is that this is not enough. It's not enough developed for us and it was not enough for this movie authors. Apart from this comes a load of pop-corn movie elements which you can see in every typical action movie: they run a lot, they shot each other a lot, and that's about all. So the specific of the mind world is left apart, and the action movie takes too much.

In this sense I say it's a lost opportunity.

Too bad for them - the movie industry - that they spoiled us with such great movies as "Solaris", "Dark City", "Sin City", "Immortel" and a lot more - some of my favourite movies ever - and learned us what to expect from such alternate reality worlds and ideas. This movies have fully developed worlds in which the original element or idea is led to take entirely over the world and action and it's doing it so good ! The action of such movies can't be the same outside these movies and in this sense we can say these movies ideas are fully grown and developed. And this is the major shortcoming of "Inception", it can be more, it's a lost opportunity to do a really great movie with a novel idea.