The movie is clearly carried out in two phases: the first one lets you in on what the main character does, hints at the monsters in his closet, and assembles the team to carry out the biggest job of their lives. It is a strained attempt at generating feeling that something big will happen when they get to the second part. The second part is a three-tier dream with a distinct design at each level with an additional fourth one that appears when the bottom drops down.
For something as visually elaborate as this film is, it lacks a good character conflict. The action concentrates exclusively on the ever-changing and beautifully executed scenery, but the characters are rather two-dimensional and there is no tension between any of them. The only pseudo-villain that we encounter in the film resides within the main character, and the villainry is better represented through fear it generates in other characters that through its actions. The "villain" barks louder than it bites. The film is too heavily concentrated on the effects while lacking in basic character development. It ends up being too benign.
True, there are many good concepts that find representation in the film: the yoga of dreams, lucid dreaming, NLP techniques of programming people into doing what you want, etc. Any somewhat-read person would clearly see the roots of ideas in this movie. The off-the beaten-path-ness of the concepts does not make them brand new, though. And for anyone who reads, this is a rather opportunistic film in a sense that it capitalizes on the fact that most will never read a thing about lucid dreams or anything in that general area of knowledge, thus pitching its concepts to an average film-goer as something revolutionary.
This film feels like a mutant baby of "The Cell" and "The Matrix". It is fun to watch at times, although scenes with the main character and his wife are mercilessly stretched, well beyond what is necessary to deliver the idea.
It is amazing that the man whose subconscious is penetrated does not put up a better fight despite his training in dream security. On the second level of the dream he just surrenders and is led like a lamb to slaughter. And you say this man was trained to defend himself when someone invades his subconscious? That's a plot hole, and a big one. Besides, who better to play a well-equipped villain than Cillian Murphy? He needs more depth and more screen time than he was given this time around. Joseph Gordon-Levitt, on the other hand, is scrumptious and understatedly sexy, a hot brainiac who can even create a kick in absence of gravity. Now that is impressive. What's a kick? See the movie. Just don't expect too much, if you are a well-read, well-traveled old soul. If not, you are gonna love it.