TFF probably was dissapointing back in the day, especially considering it came off after a consistent array of entertaining Trek films that met the set standards. But I can accept as being the odd child, it has its own charm and in a lot of ways is like TOS at its cheesiest, but with heart to go along with it (another TOS staple).
Insurrection is dissapointing still, because TNG should've had a more challenging story than this, and if the problem really was the Dominion War, just take the story and set it before the thing, or afterwards, so it could bring back the spirit of the TNG galaxy pre-DS9 (in sort, a sequel to DS9 that explored a post-Dominion War space). As is, though, its an OK story that just never belonged to the big screen. Its entertaining enough, but its also forgettable a lot of the time, and thats not good, either. So... Its so-so.
Nemesis, contrary to many, I like. Hell, I believe the first two thirds of the film are every bit as good as The Future Begins (my title for Trek XI), if not slightly better because of the morality in-search that Picard and Data go through the film. Too bad they didn't make the last third of the picture as good. Oh, and the deleted scenes shouldn't have been deleted. At least, for the most part.
All in all, I really do believe that there is only one dissapointing Trek film, in how it continues to dissapoint and still offers nothing valuable or interesting to the viewer when watching it, and every time makes one think What If. And the film that does that is, Generations.
And its not just the mishandling and ultimate insult of a death for James T. Kirk that results to this conclusion. No. Its the fact that up until then, the movie makes a total mockery of TNG and its characters. Sure, it sounds great to continue the emotion chip storyline began in season four with Brothers and continued with the Descent two-parter, and to feature the Duras Sisters aboard a TUC battle cruiser. But the film handles even those fan-like moments with great ineptitude. Stewart and Spiner try to salvage the situation but fail, and Shatner is out of his element. The destruction of Ent-D lacks any emotion, as the original's destruction and even Ent-C generated when those ships met their ultimate fate, and could Malcom McDowell have ever been misused more?
Ah well, too much time complaining about this dreck. A truly awful film that doesn't any test, let alone that of time, and thus deserves to be bitched about forever.