I hear ya, but the problem with it being "just a long episode" is that, frankly, it isn't a long episode. It's a $70M major motion picture in a tentpole science-fiction action/adventure franchise. It's a huge mistake to design such a film to be tepid, bland, and mediocre. INS is less interesting than 2/3 of the 1-hour episodes that cost $1.5M each from the series it was based on. That's unforgivable. I mean, just basic run-of-the-mill TNG episodes like "Power Play," "Booby Trap" or "Where Silence Has Lease" are multiples better than INS.
INS was a $70M wide theatrical release that played like a "straight to VHS" quality sequel (like Starship Troopers 2 or something).
Flaws or not, TFF, NEM and ID are all more entertaining as motion pictures than INS was. They were all ambitious attempts at something grand and exciting, which is far more than INS can claim to be. And when I judge INS, I judge it as a major motion picture...not just as 2 hours of Star Trek entertainment.
I'm not saying it's the worst movie ever made...but it's really the bottom-of-the-barrel for Star Trek in the theater because of how luke-warm, unambitious, riskless, unimaginative and boring it was. Yes, I'd watch it over 80% of other movies that are out there (it's still Trek, after all)...and it's better than the bottom 1/3 of TNG episodes...but that's really not the accolades you want to give a Trek movie, which is supposed to be a big, fun "event" film.
By the way I measure things, it's just a damp squib of the worst kind.