I actually only bought 12 Monkeys last year, but I really enjoy Gilliam’s camera angles, production design and odd stylistic flourishes (that weird accordion music in the opening credits!) in the film even though he’s basically a hired gun. (A favorite image is the ominous warning spray painted on the side of the building where Pitt and his people are hiding out.) The film amusingly looked a lot more expensive than it actually was, which I really like (Dark City, the Ebert favorite, is another great ’90s example of this.)
There’s a really long documentary on the DVD that explains all this, which is interesting in light of Gilliam’s infamous recurring troubles making all of his films. I have not seen his Don Quixote movie (I’ve also never read the actual book.)

The woke crowd apparently went after Gilliam a few years ago for…something, but I don’t remember what.

Willis and Stowe are reasonably good together which is kind of a miracle when you think about it, I think in the hands of two lesser actors their relationship would have fallen completely apart on screen, not because of PC issues today but because one stops to consider just how AWKWARD their relationship is.

Pitt’s performance comes across as weirdly....adolescent for him. I mean by then he was doing serious stuff like Se7en and I don’t think he’s been asked to play too many darkly comic loonies since then. You probably already know that he got nominated for Best Supporting Actor for it!!!
Christopher Plummer is barely in the movie at all, I’d remembered him as having a larger part but he didn’t. Hell he’s probably more in Star Trek VI.
The whole plot twist where it turns out Pitt’s gang were just kids releasing zoo animals, and that David Morse was the real bad guy, doesn’t really work that great as a fakeout.
I’ve never seen La Jetee either, the 1960s French movie (a series of still images, IIRC) that inspired 12M.