Let me qualify the following statements by saying that there are things I really liked about Inception, and if it had been made by virtually any other person, I would be more forgiving.
But this is something written and directed by Christopher Nolan, and therefore its flaws are all the more glaring. As a story, Inception is all setup and no payoff, all concept and no heart – all science, no humanity.
By now I’m sure you’ve heard all you need to about the film. Inception is about entering dreams in order to steal information from a person’s subconscious. Leonardo DiCaprio and his squad of dream-raiders do this for a living. They’re very good, but it’s highly illegal.
The dreams have a ton of rules (much more than the similar but comparably less complicated[!] world of The Matrix). Get killed in a dream and you wake up. Dream time is faster than real time. You’ll never remember the beginning of a dream, and you need an object to carry around with you so that you can hold it and feel if it is different than the object is in reality, and thusly know if you’re in the dream world or the real world. You can’t change too much in a dream or the dreamer’s subconscious will rise up and attack you. Pain in a dream is as real as anywhere else.
Imagine all this mess as the first half an hour of a film.