I think GEN fails in many ways, it is more of an overblown episode than a real movie, the sharp lighting of the ENT interior is not well done, music and cinematography are pretty underwhelming.
I also totally agree that it does hurt the movie when a chemical rockets hits the sun in a few seconds or when you ask yourself why Kirk and Picard have no chosen an earlier moment to get out of the Nexus and stop Soran. But when some contrived nonsense serves a point, in these instances to speed up the moment between rocket launch and hit respectively to simply get Picard, Kirk, Soran and paradise somehow together via a sci-if-ish gizmo, it is, at least in my opinion, excused. I view it as lesser evil than bad dialogue, bad ideas, bad acting and thematic voids.
I would phrase the plot hole thing slightly differently, in my opinion the problem is that GEN feels a bit clustered. The subplots with Data and the Duras sisters do not really harmonize well with the already unharmonious Nexus thingy.