Avatar

Cinema, just like books, music, video games, the spoken word, the whispered word, etc., is a medium. It is a mere clay in the hands of a potter. Sometimes, it is mishandled. The results are devastating and catastrophic.
Having seen the critically acclaimed, massively beloved, and as fate would have it, most highest grossing film ever (it's currently January 2011), that being Avatar, by James Cameron, I can honestly say that it deserves that title.
This film is one I can definitely consider a masterpiece. I must remain truthful- the story is one I've heard in various places. Essentially, there are squatters from a faraway place. They seek something extremely valuable, and they're willing to lose something else in order to obtain it- namely, their humanity. These squatters are likely thousands of times more powerful than the natives they are stealing from, and will stop at nothing to get what they want. One of them, though, will somehow realize that what they're doing is morally reprehensible, join forces with the natives, and work against the squatters.
The execution of this film was pure genius. I have absolutely no gripes with regard to the visuals- I thought it was ingenious his use of what appeared to be fan worms for one scene, and this is one film that would have been amazing even if it had no dialogue. In fact, if it were nightmarishly written, if the actors were wooden, if the music was replaced a capella death metal (no offense to death fans- I just find your music incomprehensible- try listening to light jazz and you just might understand me) and if Sigourney Weaver wasn't in it, the film would have been amazing simply on account of its incredible visuals. Fortunately, this wasn't the case- it was very well written; the story, though common, made sense, and the acting was very good. The music was excellent, and while it's not exactly what I would have chosen, it was still very good, and then to top it all off, Sigourney Weaver was in this movie! This woman has slain aliens and portrayed Diane Fossey. One of those is more than sufficient for a lifetime.
So in addition to being well cast, written, etc., what else can I say about it? Ah yes, execution. Essentially, all these brilliant elements were carefully, dare I say lovingly assembled into a piece of art that defies the boundaries of age, culture, language, and hatred of science fiction. Yes, those who hate sci-fi (AKA Blaspheming Heretics!) enjoyed this film.
In all, it was well put together, and after many years of hard work (it all began in 1994, my birth year) Mr. Cameron has accomplished something truly epic. So awesome, in fact, that the (presumably) unbiased Wikipedia calls it an 'epic' film.
If you haven't guessed already, I absolutely loved this movie, and can recommend it to just about anybody.