Star Trek III is a great film IMO.
Just wanted to go way back to the beginning of this thread and address a very early quote from there, which I found both very amusing and interesting:
EnriqueH said:
Kirk.
They stopped at a Starbase on the way back to Earth, and she saw him at the bar looking depressed and forlorn, and tried to help him feel better. He takes her aboard the Enterprise to his quarters. At which point, she took the data tape from Kirk's quarters.
It's probably what Kirk is thinking about when he gets into the turbolift and wipes his nose.

So that's how Valeris got the data tapes!
Unless I've misunderstood what you were saying, of course, in which case I hope this doesn't bother you - perhaps you simply meant that he befriended Valeris because she was a Vulcan, he likes Vulcans because of Spock, etc, and just 'took her to his quarters', and nothing else.
But, unless I'm mistaken, I'm assuming that you implied something
else entirely with that statement - humourously, you were saying that Kirk thought Valeris was hot and fancied her (which isn't hard to understand), and that she seduced him, they...well, fooled around together - and then she stole the tape from his quarters while he was sleeping and snuck off.
Am I correct? Or did I simply read way more into what you wrote than you intended, and the part about 'taking her to his quarters' wasn't meant to be imply that they had sex at all? If so then I apologise - it just seemed funny to me.
In fact, although Kirk has by the time of TUC obviously calmed down his, uh, libido since his younger days back in TOS, having an easy lay with a chick and this coming back badly on him later on would actually be a good way to showcase his vulnerability to women. So it could make a lot of sense potentially.
It might even explain why he seems uncomfortable with Valeris in TUC - he seems to find it weird that she enters his quarters, and looks like he's feeling either confused or guilty about something. What was he thinking? "Hmmmm, is this that same girl I was fooling around with a couple of months ago except with shorter hair and in uniform? It is! Damn this is embarrassing."
As for the other comments on Star Trek III in this thread:
I actually thought Bill Shatner's acting in TSFS was some of his very best. Even when it was over the top, it worked because of the extreme nature of the situation - people sometimes genuinely do act crazy or yell bizarre things when they're in a really extreme situation.
Hence, Kirk killing Kruge in self-defence was brilliantly (even if somewhat hilariously for the audience) over the top. Who can ever forget those gems: First, when Kirk leaps at Kruge, and yells: "Arghhhhhhhhhh!" in a completely hammy way, and second, the unforgettable: "I! Have had...enough of! YOUUUUUU!"

A scene like that could only ever have taken place before the 90's.
I am of the opinion that Bill Shatner's acting improved significantly between TOS and the TOS films. Anyone else think the same? He was often great in TOS, don't get me wrong - but he seemed to have acquired more subtlety and grace as an actor by the films, especially from TWOK onwards.