The Final Frontier wasn't that bad, let alone the complete, embarrassing trainwreck it's often claimed to be. Pretty good interactions with the big three, interesting if out-there story, decent resolutions. Plus I tend to enjoy slapstick in general and most of it in the movie was at least OK. A lot of the complaints seem centered on there's too much humor, especially slapstick, hating the idea that Spock had a half-brother or considering the special effects to be bad.
I have a theory on The Final Frontier.
It's hard for me to say, because I'm one of the few human beings on the planet who actually really like the movie (I actually put it higher in my ranking that TVH and TUC)...but objectively, it
is a mess. It looks bad, has sloppy writing, and some unnecessarily silly moments that just kill the momentum.
That said, it is also the closest in tone and plot as anything else produced in the
entire franchise to the original classic series, which I love! So, why was it so hated? Here's my theory: Shatner. For the most part, people were prepared to hate it because of the polarizing effect William Shatner has on the fans and pop culture in general. Shatner told us to "get a life" in 1986 (in a totally tounge-in-cheek moment, btw)...and damnit...the fans were ready to make him pay for that. So, when a relatively decent but certainly flawed film premiered in June of 1989 with his creative fingerprints all over it, it was the perfect opportunity to get all that frustration out on the guy who made everyone feel like a worthless geek and who had been rumored for decades to be an insufferable jerk with his peers and fellow actors. And people pooped all over it as a result.
It's funny, because TMP was criticized at the time of its release for being too sterile, boring, and ponderous...and not having the heart of the original series. TFF was almost the exact opposite of that, and it is equally (if not more) criticized.
It makes me wonder how TFF would have been received, given the same production values as TMP and a little clean-up on the script and story, if it had been the first Star Trek movie.