The effects are passable. They're a lower tier concern for me. The story and characters and really poor humor that sandbag this film.
I agree and disagree.
The effects are not horrific. It's not Birdemic. But for a film made in the late 80's, they are noticeably bad, particularly in comparison to what ILM and especially Doug Trumbull and John Dykstra had managed to do on earlier Trek films. That said, the one thing I do like in TFF is Bran Ferren's use of rear projection for the viewscreens and windows. I think that gives a more realistic feel than the constant use of blue/green screen.
The humor I 100% agree on. It was a classic case of a Hollywood studio looking at the success they had with one film (TVH) and trying to jam the same thing into another film (TFF) where it didn't belong. The humor was, in most cases, completely forced and out of place. In TVH, the humor was organic and character-based. In TFF, it felt forced and almost slapstick.
I don't really agree about the characters. I felt they got the characters pretty much right. I don't think the trio of Kirk, Spock, and McCoy were ever portrayed on the big screen better than in TFF. And while there were a couple of cringey moments for the supporting characters, I still thought they generally did a decent job with them.
The story is where a good portion of the flaws come from, largely in the fact that there are some major plot holes, as well as the lack of a satisfying ending. Also, I think Shatner, as a new director, didn't spend the film's budget wisely and that hurt the ending as well.
There are some bright spots, though. I think Shatner was actually a pretty good director from a visual standpoint and shot TFF more like a movie than any Trek film since TMP. I love the production design and the cinematography. The score is absolutely beautiful.
I personally put TFF in the category of a good, but flawed, film.