Alien³ is a strange film. Some of its problems inevitably stem from its post-production issues, but there's also the question of intent. It's three films in one; first is a sequel to Aliens. That storyline takes about an hour. Then it's its own film for about forty-five minutes. Then it's the final film in a series for the last ten or so. Characters move between these phases, but not necessarily subplots and the filmmaking techniques even change.
Disjointed might be the politest description; incredibly messy also works. Gloriously messy might be the best, however, because Alien³ is glorious. Fincher does an outstanding job directing–and his composition techniques also signal changes in the film's phases–with wonderful Alex Thomson photography. But the Terry Rawlings editing really brings the whole thing together. It's a lush, dark, dank film.
All of the acting is great, especially Charles S. Dutton and Charles Dance. Sigourney Weaver is fantastic (of course, it wouldn't work at all if she wasn't). She and Dutton occasionally get some terrible, trailer-ready lines and they push through them. It's in the quieter moments Weaver really shines; it's simultaneously too obviously on her shoulders and just right.
The special effects are fine. The practical ones are outstanding and the production design is phenomenal.
Additional good supporting turns from Danny Webb, Ralph Brown, Brian Glover, Pete Postlethwaite. Paul McCann's good even if he inexplicably disappears (one of those post-production issues).
Great Elliot Goldenthal score.
In pieces, Alien³ is excellent. All together, it's still good.