Warning: Spoliers
Its been awhile, but I remember most of it. The key to this movie is to remember that Tom Cruise is really dead (actuallym, more in a state of suspended animation) for 90% of it and the world he exists during in this 90% is not real.
Tom Cruise dies very early on in the film (I beleive it happened in the car crash, but I'm not sure). Before his death, he has signed up for a new service that will put his body into a state of suspended animation upon his dreath. This was done before the film started, so we have no idea he did it.
Most of the film take place with Tom in suspended animation, living his life in a dream state. He is not aware of this (and niether is the audience till the end of the movie) nor does he rememebr the deal he made to have the company preserve him after death. The dreamstate is supposed to provide a very pleasant "life" for Tom, but for some reason, he brain will not accept it. His brain begins to provide stranger and more horrifying events in his life in an attempt to resist. Since Tom has no idea he is not in the real world, these event are very confusing to him (and the audience).
The company which is maintaining Tom's body realizes there is something wrong and sends in a "tech support" character into Tom's world. Eventually this character is able to convince Tom that everything he sees is imaginary (a result of the dream state) and that things have gone horrilbly wrong. (I felt bad for Toms lawyer when the tech support guy proved to him that he didn't exist, that was one of the few good scenes in the film).
The Tech support guy offers Tom the choice of either restarting the dream state with the problems resolved or reviving his dead body and letting Tom live again in the real world (no explanation is provided as to how they can do this). Tom choses the real world. He is then told that in order to leave the world of the dream state, he must kill himself in that dream world. In a massive leap of faith, Tom then jumps off a tall building in the dream world and kills himself. The final scene shows Tom waking up in the real world back in his real body (presumably just in time to begin work on Minority Report (LOL)).
There were some real neat ideas in this movie, but I had it figured out by the third time they showed that stupid dog expiriment on TV (it was a not so subtle hint as to what had been done to Tom). Overall, It was thought provoking, but only the ending was truly interesting to me. The scenes with the lawyer discovering that he was not real and Tom making his leap of faith were quite good. Too bad they came at the end of such a disjointed, poorly made film.