To me it wasn't "prequel level" bad, but it does have its major problems, and unfortunately those all seem to be tightly woven to the plot. The prequels were easier to edit because there really wasn't much of a plot there. You could honestly remove the vast majority of one of the SW prequels and still keep the "plot" intact.
Star Trek 10 on the other hand, has a plot, kind of a lame and unimaginative plot, but a plot none the less. And the whole film revolves around this plot, which is what a film should do. I think the best that could be done would be to remove the little things that bug people and call it good from there. If there was a way to remove the Picard clone thing that would be kind of cool. I always cringe when Picard is looking at the picture of himself at the academy and it is a picture os Shinzon (sp?) in a SF uniform. Being a clone of Picard doesn't make him anything special really. I suppose this could be cut. It would also be cool to think of some way to make reference to Lore somehow. Not sure how, but there are seven season of TV show and three other movies worth of dialogue to rig something up with. Something along the lines of "I am not sure if this is a good idea, remember the last time we found one of data's brother." and Data rationalizing why Lore was bad and why the odds of this new one being evil are 32000000000000000000000 to 1 or something like that.