If you don't buy time travel, stay away from this one. I personally get a big kick out of messing with the space/time continuum, preferably when it doesn't involve a time machine or a spaceship. Wormholes, unexplained phenomenon, stuff like that: it's all great. Twelve Monkeys completely sucked me in, entertained me, jarred the cogitator, there was even a little intense bit or two. I had to rewind the first ten minutes or so and watch it over because I wasn't paying close enough attention.
The best part of it all, perhaps apart from Brad Pitt's wacky impersonation of a lunatic, is the choose your own ending. (Spoiler here) Since James Cole is present at the airport at age 8 and also as an adult, even though the adult is killed, the boy can grow up, go underground, and come back to try to save the human race for a limitless number of times, potentially until he gets it right. Who knows, after enough attempts he may even live happily ever after. On the other hand, all Witchy Lady Scientist has to do is slip a little poison in Bioterrorist's champagne, assuming that is, that he didn't already release the virus, which he almost certainly did. But that would potentially save al the other cities. Just pretend Philadelphia is a house with termites and tent it.