Generations is really the only Trek movie I find unwatchable.
It has its moments but falls apart when Picard enters the Nexus.
The trouble with Generations is
the Nexus, but more particularly that the entire plot hangs on it. We're constantly told that it's this wonderful realm that nobody ever wants to leave, but because Picard doesn't enter it until the final act we get a very rushed view of it. Jean Luc ends up leaving far too easily because, hey, the plot requires him to see through the facade and then convice Kirk to do the same. What that movie really
needed was to have thrown Picard into the Nexus far earlier. They should have shown more of Picard being genuinely seduced by the fantasy lifestyle of having a wife and kids, but only gradually coming to realise how superficial and fake it all is. They could even have gone the whole hog on the It's A Wonderful Life
thing with somebody (the Guinnan echo?) convincing him that he needs to leave because his absence from reality makes such a difference, maybe show him flashes of how real life gets affected by him not being there. Instead, it just seems to be seeing those fancy Christmas decorations blowing up which snaps him out of it. Which happens, like, thirty seconds after he enters the Nexus, and only then because the plot demands it. As a concept the Nexus has got potential, but that movie just blows it all.