They say it's easier to write a sad song than it is write a happy one. The same goes for reviews. A flawed, or terrible film gives you plenty to moan about. A movie were everything about it ranges from good to sublime leaves you with very little to say. And so it is with 12 Monkeys were the only complaints I can dredge up are tiny little niggles.
I'm not saying the film is perfect, but it's very close to it. The story is properly compelling, it's well told, well paced, well acted etc. It's also visually one of the most interesting looking films I've ever seen. There is often a surreal quality to the images with extensive use of Dutch angles (camera slanted to put most things in the frame on a diagonal slope). I wouldn't call it a pretty film, just that it's visually inventive and constantly attention grabbing in a pleasing way.
I think the director himself once said that the acting of Bruce Willis and Brad Pitt has a tendency to split audiences. Most people think one gives a great performance and the other one a weak, overly mannered one. I've previously thought Brad Pitt's acting was a bit fake and unconvincing. Over time I've grown to think he's good, not outstanding or anything, but appropriate for a mentally unstable person.
The child actor during the airport scene is a minor weak link as he seems to be over-emoting like crazy with his eyes. He's not bad or annoying, he's just not note perfect.
Logically the film is not one hundred percent watertight, though I doubt many, if any, time travel films ever are. There might be some holes, but the film is too good to be affected by them. Why don't they go further back in time and correct their own mistakes (the airport scene at the end throws up a few questions along this line)? A question like this is kind of pointless as it's simply more dramatic and poignant the way it is.
This is one of my all time favourite movies. The script and direction are as good as any film I've ever seen. Bruce Willis gives his best performance and basically everything else about the film is either good or borderline perfect.