It's Alfre Woodard. Of course she was good
Her scenes make that movie far more watchable. Alfre somehow managed to outdo Patrick, which is hardly an easy thing to do. Her response to Captain Picard with "...
you'll kill me?!" is spine-chilling, every time. Followed by her mocking Picard's "evolved sensibilities" bit, and then making the Captain Ahab connection. Alfre is simply amazing throughout the movie, outshining pretty much everyone else.
But that's the best acting in any TNG movie, aside from anything said by Khan or Chang.
As for worst acting in any of the first 10 Trek flicks, my candidate also goes back to the same ST:FC movie! The "drunk acting" Troi was doing is my candidate for the worst. Made worse by the worst sub-cornball joke about not having time after more cornball about having to fit into the culture -- for which getting drunk is the worst possible thing to do if one wishes to remain incognito because she'd be spilling her guts metaphorically before doing so literally and yet the script has Troi doing all this and poor Marina being stuck in having to do it as a result. TNG's side characters really get put to the side in their four movies, but Troi getting drunk is out of place for her character to begin with, never mind Marina's acting makes it all look like a self-aware joke from the audience's perspective. It's a misuse of Troi so if Marina was chewing the scenery because of that, who could blame her? Still, Troi claims she had to do it in order to get intel from Cochrane. Maybe Dr Crusher should have been there with her anti-alcohol bat-bills in her medical kit...

The scene didn't work and the acting felt too forced.
Having said that, the wonderful scene in TMP where Kirk says he needs Bones badly (per JonnyQuest037 above) is pretty bad as well. Still, alcohol and Star Trek do not mix. Unless you're my ex, he needed booze for everything. Even stuff he liked, which was what he preferred to watch...