I think the film is pretty much perfect and most of the stuff added in the director's cut was not needed but I really wish the scene that made it clear Preston was Scotty's sister's son had been left in Wrath of Khan. I knew what was going on because I read ever Star trek book I could get a hold of including the novel(which was pretty good), but I know a lot of people are confused by Scotty's relationship with him.

This may not be the same thing but it still feels like it was needed. This was never filmed but the novel of Wrath of Khan was based on an early draft of the screenplay and from what I remember(it has been years since I read it so forgive me if I don't get all of the details right)it explains that Preston had been friendly with Savik and didn't judge her for being half Romulan and he had a crush on her that Savik kind of returned and kind of just found silly, but she never did anything about it, I wish that scene had been filmed and included in the movie. Why? because it explains Savik's cursing and the fact that see cried when she saw Preston's broken body. I also believe it explains why Scotty brought him to the bridge instead of sickbay. In the movie Scotty just looks like an idiot but in the novel Preston asked to be taken to the bridge so he could say goodbye to Savik since he was her only friend on the ship. I really wish this had been filmed and included.