III to me has some good, and some bad. I thought this marked a turn where the characters started to become parodies of themselves, rather than playing it straight. Which I'm fine with in STIV, but that shift I feel was detrimental to the series as a whole.
Thought the "no, you can't have a ship and go out to this classified area you were just at" made little sense, given how important Kirk was to the federation at the time. It was easy to explain their situation to the brass, given McCoy's stuff going on. So the stealing the ship and sabotaging the excelsior portion of this felt a bit cheesy to me.
The main conflict still holds up well. I like genesis, it's a good sci-fi theme. I like David and Carol. The enterprise destruction was cool. Tough time buying Back to the Future guy as a klingon (I have no idea why his name is eluding me, and lazy to look it up). Love how David's arc played out.
End scene where Spock returns sans memories is pretty touching.
So good and bad. Like a 6.5-7/10 for me. I skip it on most rewatches, but don't skip it ALL the time (like V, Insurrection, Nemesis)