People say the original is better, but I think they're just trying to be cool. This is definitely one of my favourite movies, one of the few movies that I consider absolutely flawless. There isn't a single thing in the movie I would've done differently. It's brilliant.
As for what it's about, it's not that difficult to 'get' if you pay attention - basically David Aames, the lead character, signs himself up to this new technology (you don't know about this until the end of the movie) that freezes your body in cryojenics (something like starwars) and controls your thoughts, so that you have lucid dreams. You get to pick how you want your life (dream) to be and it also works upon your subconscious to make your life (dream) 'perfect'.
After David's face gets fucked up, because of his crazy stalker Julie Gianni, and he starts going crazy himself - he signs up to that program, and overdoses on pills shortly after.
The 'dream' then picks up the night after he's ditched by sofia at the club, and is replaced with a much better ending than what really happened. Unfortunately even his DREAM gets fucked up (glitch in the program) and that's when things just get really nutty.
After all the nuttiness has you thinking the movie is really about him being a murderer and that sofia/julie are really the same girl, things finally make sense when things are explained at the end of the movie, in a very surreal way, that it was all part of this futuristic program he signed up for. The movie ends off in a peaceful but still very sad way.
I think that everything from the choreography, direction, acting, plot/story, dialogue, to the SOUNDTRACK is perfect. 100% perfect. Everytime I hear that song from Sigor Ros I get goose bumps. It's also a great movie to coerce unsuspecting girls into thinking you're intellectual, sensitive, and deep about and makes them a lot more prone to fooling with you right away
Another movie that I think is equally flawless and also pretty highly acclaimed is Requiem for a Dream. This movie will also toy with a girls emotions and might soften her up for a little fooling around with afterwards. ;)