Which movie haven't you seen?
Star Trek V: The Final Frontier
I also only recently saw The Undiscovered Country (watching it as an appendix to my Voyager [re]watch-through).
This movie has a few good lines and we get to see a bit more of McCoy's backstory, but otherwise it's crap.
It's also the only ST movie I ever considered walking out of the theatre over, as I found it that