Definitely the best philosophical/psychological thriller on film. With a big budget for special effects and casting, you wouldn't expect less.

My only gripe with this, moreso than with other films of this genre, is that it seems to be an analogy gone overboard for the purpose of not only capturing the attention of intellectual audiences during the movie(you need a more limber brain to keep up with the erratic plot development), but for the purpose of intentionally keeping audiences thinking about what the hell happened after the film is over - because this is one of those movies that ends on an unclear tone, like Lost the series. In that way, it seems that much of the cat-and-mouse mental work you do to figure out the mystery throughout the film (is that a dream? is that real? etc) is wasted effort, and an easy way for script writers to ensure that they can get away with doing less to have viewers wanting more. It seems that the complexity of this dream world is deliberately contrived so that viewers can feel self-satisfied afterwards, thinking, "Hey, that was complicated as hell. But I figured it out. I'm awesome, and this movie is awesome."

Beyond being a symbolic representation of the human psyche, the plot of the film is ridiculously silly. I don't want to give away any spoilers, but I will say this: instead of entering into someone's dream to plant an idea like a cool secret spy with extraordinarily contrived plans with cool gadgets and stuff, why not just use hypnotic suggestion? Or, hell, why not clone the other person, or make a cyborg? As silly as that sounds, it's way more feasible than, well, the plot of this movie.

All that aside, this is a good movie. If I were you, I would watch it. But, be in the mood, this isn't another brainless shoot-em-up.