I think TFF was a mixed bag. He was GREAT in some scenes like everything in the observation room (Spock's "Sybok data dump," secret pain scene, and post climax wrap-up)...and hammy in others (aboard the shuttlecraft, in the brig, El Capitain), so this film is probably the best representation of his TOS performances (ups and downs) quite honestly.
TUC was my least-favorite, because everything in that whole movie just felt like a big wink-and-smile at the audience. Nothing felt legitimately dramatic.
GEN was odd, because it was Kirk as written by the TNG writers...so it felt off a lot (Scotty spouting TNG levels of technobabble always takes me right out of it). Shatner's performance with Picard on horseback in the Nexus was great though, and I (unlike many) LOVED how he played the death scene.
I guess I was never able to get past the whole El Capitan scene. The Observation Room scenes were not bad. I also loved that set. I always wished Meyer was able to use that set in TUC.
I actually sort of liked Scotty spouting a little technobabble. TNG always made everyone seem like they were more intelligent then the original series (I don't think that was intent), this was Scotty's chance to prove they could be Mr Smarty Pants in the 23rd century too. So take that 24th century
