There's 101 scripts of Alien 3 floating out there on the internet - this one, credited to Hill and Giler, presumably has elements from the many other drafts done. From memory (which is vague) it's quite close to the final film.
It's written in that stripped back, pared style that Hill and Giler used on the first movie. It's not as good as that or Aliens though for a number of reasons. The basic story is flawed - Ripley crashes on a prison planet, which sounds kind of cool but nothing much is done with it. It's all male, there's a few religious nutters and some nasty types and a disgraced doctor - nothing overly complex or interesting. Certainly none of the characters pop like they did in Aliens.
The structure is closer to Alien - one creature on board knocking off everyone one by one. The first movie had the benefit of surprise - the people didn't know what they were dealing with, we didn't know who our hero was going to be, we didn't know Ash was going to be an android, etc. This one we know Ripley's our hero; there's no Android reveal; we know the alien is bad and the Company is bad. There's no weapons so basically it's the alien knocking off cast members periodically in un-memorable ways.
It is good Ripley is pregnant, and that Bishop II turns up and that Ripley kills herself at the end. I liked the character of Dillon, who helps Ripley. I didn't mind the doctor. But the prisoners all blended into each other - rich individual characterisations was never particularly Giler and/or Hill's strong suit.
It's a depressing movie - they kill off Hicks and Newt in the first few minutes, kill off Bishop later on. No one survives. It does have the integrity of that vision, it must be admitted.