It was basically a space zombie movie.
And I like RedLetterMedia's take on a related aspect: TV Picard and Movie Picard as being two different characters, at least in how they're written.
The movie Borg are different than they were originally presented in TNG. Voyager started that change, making the Borg more personal. They were all nice and impersonal before, just as described in-show by Q: More of just a singular massive entity. Having their centralized "leader" even bothering to converse with an individual person seemed so beneath them, like trying to have meaningful conversation with a mouse.
Movie: Yup, they're just scowling zombies that get shot or whacked with various large sticks.
I love Generations. They, apparently, shot it right after they wrapped up the final season with a relatively low budget.
They also spruced up the effects a bit.
(Though there was that cheapass use of stock footage for the exploding Bird of Prey.
...did the original Power Rangers movie even use any stock footage from the show? That's a heck of a bar to set.)
The Nexus did seem kind of wacky as a concept. A place where primates can go to live out an ideal life, but leave at any point in space and time? Ok. Sure. Why not.
Or let's just say it was made by powerful aliens and sent on its way through the Universe, kind of their alternative to a Stargate-seeder ship. So it's actually intended as a transportation system, and the whole "live your dreams" thing was just their idea of an awesome lobby. The destructive energy streamers around the outside are just to keep out the riff raff.