As far as comparisons to The Final Frontier, it has different kinds of problems. TFF is dumber, but Nemesis was more offensive to fan sensibilities.
For a direct comparison, Generations is actually more like The Final Frontier, and if it's not as stupid it's at least more boring. It also tries to provide the type of nostalgic ending to TNG that the series already had. In retrospect, I think everyone admits that First Contact basically did the only thing a TNG movie could have done that really justified extending the series any further at that point, by bringing back the most popular enemy alien race and giving us the kind of story that would have been too expensive to do with them on TV. TNG wasn't action-oriented enough to warrant more than one movie like that, and the other things the show did had already been done successfully on television.