12 Monkeys is a convoluted tale of time travel, insanity, apocalypse, and who-done-it, with some romance thrown in. What I enjoyed most about it was the twisting and ambiguous path it followed, which was fresh and well thought out, to a point.
Bruce Willis plays Cole, a prisoner in a post-apocalyptic future recruited to do some dangerous time-travel work in the past for a group of very odd scientists. The goal of the work only becomes apparent later, and by then there is confusion about whether Cole is really on the mission he thinks he is or is just deluded. Brad Pitt has a major supporting role hamming it up as another who may or may not be insane.
Ultimately, while I don't think the film does full justice to its premises and possibilities, it does well enough to be entertaining and thought provoking. Director Terry Gilliam's surrealism adds much. The acting is very good on the whole, itself rather surreal in some of the supporting roles. There is some violence showing how disturbed Willis's character is, not bad for an R-rated movie. It's definitely worth seeing to judge for yourself what it's really about.
I want to comment on the things you think about after the film is over, to see how well it holds up. I'll have to go into details you may not want to know about if you haven't seen the film yet, thus the spoiler alert. If you'd like to know what my general conclusions are, without any spoilers, just skip to the last couple paragraphs headed "In Sum."
*SPOILER ALERT*
Madness
There are many points designed to suggest that parts of the film are delusions, but they're balanced by points seeming to show the opposite. There is the over-the-top strangeness of the future (the video ball, serenading scientists, etc.), the obvious parallels between the psych ward and the future prison (similar panels of doctors/scientists, the two guards, etc), the voice that calls Cole "Bob" (moving around as if in his head, though it seems to belong to the wino too), the music in the ruined department store (apparently a premonition (or something) of the time Cole is there in 1996), the lion and bear (again paralleled in 1996, unlikely denizens of a wintry abandoned Philadelphia).
But then Cole's disappearances, the French that Cole himself doesn't understand in WWI (yes, it's real French), the photo of Cole from WWI (though nearly impossibly convenient), the WWI bullet, Cole's knowledge of the boy in the well prank, all seem to settle things conclusively against delusion. That is, unless we're to imagine that not only the future but the whole film is delusions, of Cole (or Bob) and/or Railly, in line with her own fears and the comment by the virus culprit (Morse) that Railly might be succumbing to her Cassandra syndrome. Confusing? That's what Gilliam was aiming for.
In a way, the view that the whole film is largely delusion seems the most coherent overall interpretation, in that it can explain away all failures of logic. But it has trouble explaining how good the logic is. The film, strange and muddled as it is, really does seem far too lucid and coherent to be primarily be a string of delusions.
The End, Time Travel
The ending has stirred much debate. The woman sitting next to the culprit on the plane is one of the scientists from the future. She is presumably there to do exactly what Cole said the scientists planned to do, gather a sample of the virus from before it mutated. According to Cole, the scientists didn't send him to change the past, which he says is impossible. He was sent to gather information, which he did. We must assume that the sample is gathered and that this enables humanity in the future to return to the surface of the planet. It doesn't help the 5 billion killed.
That appears to be the basic sense of the ending, but it has its own loose ends. Why was Cole given the gun, if not to try to change the past? (Jose's line that it's too bad they didn't get the information sooner makes no sense to me in the context of time travel.) The scientist introduces herself on the plane saying, "I'm in insurance," which is a great line if she's a backup for Cole, in case he fails to stop the spread of the virus. But that too implies he could have changed the past. Even getting a sample of the virus seems to change the past. Trying to figure out the point of all of this is further complicated by the the fact that we are shown the virus being released by the culprit when it was being inspected at the airport. By the time Cole tried to shoot him it was already too late. This adds to the pathos, and the confusion.
Some views of time travel allow the past (and future) to change. It could work this way. Young Cole goes to the airport, there is no shooting, he survives the virus, and is eventually sent back, where he is shot, witnessed by young Cole, who survives the virus and is eventually sent back, where he remembers the shooting and gets shot (the scene we see near the end of the film). This would allow one more twist in the film, one suspected by some optimistic viewers. Railly, recognizing the boy Cole, would tell the boy to remember that the culprit wasn't the 12 monkeys gang but Dr. Goine's assistant. Then Cole could conceivably grow up and loop back one more time, this time preventing the virus from ever being released, and getting the girl. There is no hint of this, however. Had the filmmakers wanted to hint at the possibility, they easily could have (by having Railly whisper something in the boy Cole's ear, for example).
In Sum
All in all, the film is stimulating and fun but ultimately more frustrating than it might have been. I like a film that provokes thought, but I tend to prefer one that rewards it with additional insights and clarity. That only goes so far here, and then things seem impossible, muddled or otherwise unsatisfying. There is a certain postmodern sensibility that prefers just this kind of lack of clarity and incomplete logic. I don't know if that was intended here or just came about accidentally (I suspect some of each), but if that sensibility is your thing, you should love this film.
The DVD anamorphic video and 5.1 audio quality are fine. There is commentary track with director Gilliam and producer Charles Roven, and a full-length making-of documentary. Both are interesting and worth the time, but don't expect answers to the puzzles the film leaves, other than a hint or two expressed as personal opinion.