STTMP: Not much like TOS. Different look, a more mature outlook to AI, but also a less warm feel.
STII: Closer to the feel of TOS: Still, a "villain" centered story, there weren't too many villains in TOS..and in this case Khan was underwritten in the movie, but redeemed by a great performance. Space Seed was better written for Khan. It was more military and had more battles.
STIII: Nothing but "family", the crew is even more close at this point. The Klingons dont feel much like the 60s Klingons, but there is something of a tv episode intimacy in this movie.
STIV: A lack of a central villain, a slingshot around the sun, lots of humor like several popular episodes, and a message. This feels a lot like a big budget TOS episode!
STV: SHatner kept this one from feeling like a TOS episode. Illogical characters, humor at the characters expense, bad writing, poor planning...about the only thing that feels like TOS is the FX.
STVI: Meyer made this feel like his own, there are things Roddenberry never would have put in this movie.