The problem is that the movie was a cash-grab, that was rushed to Theatres just after TNG went off the air. I was lucky enough to hear Brannon Braga and Moore talk about the movie in person. They stated that originally Kirk, Spock and McCoy were there on the Enterprise B, but there was no time to re-script the lines for Chekov and Scotty - they literally just lifted the dialog and gave it to them. So we have the weird bit where Chekov (McCoy) says "you and you, you've just become nurses, lets go". It makes sense for McCoy to say that, but not Chekov.
They tried and failed to get Nimoy to direct and then Meyer. Both refused. Berman informed Nimoy that there was no time to rewrite the script, that they were already in production, so Nimoy walked away.
Moore even stated that Nimoy's complaints were valid. It all feels made for TV, you've got a workman like director in David Carson, who has not directed a big budget movie since. You've got (actually kind of lovely) TV music that totally fails to score, especially in the action scenes. They'd wanted Goldsmith of course - but he wasn't available. Braga said they realised about the plot hole of leaving the Nexus (any time) but didn't have the time to solve it. Instead they hoped the charisma of Stewart and Shatner would paper over the cracks. You've also got TV quality actors with the Klingon sisters and their inclusion is just off. It's a side track that goes no where. Flab like this makes the film harder for the non-fan to appreciate the movie.
Some of the VFX in Generations is great - the energy ribbon, that shot with Soran on the mountain. But time pressures meant that even footage filmed for Encounter at Farpoint is re-used. Even the saucer crash didn't work properly, they were able to cobble something together that kind of works, but the leading edge of the saucer kept lifting up.
For me - and this might be unpopular, the biggest weakness is Shatner. The man is an acting powerhouse, he was the leading man in six pretty great movies. But in this one, Shatner plays Shatner, not Kirk. Shatner loves horses and Dobermans, does Kirk? Was this really Kirks fantasy? Where was Miramanee or Edith Keeler? The problem for me is always that Kirk isn't in the film except for right at the beginning.
Over the years, I've mellowed on the movie, I like the bright colorful approach and the attempt at a complex story - rather than revenge plots filmed in dim lighting. The first half of the film really works, but it's all dragged down once they enter the nexus.