Why is it bad? because it has a car at the beginning? I dont get why it is a bad film.
Shinzon is an absurd villain with motivations that make absolutely no sense. "The Romulans were mean to me, so I need to destroy Earth!"
B4 was a dumb idea. If you really want to bring back another Soong-type android, why not bring back Lore? The only purpose B4 served was to give the writers the option to bring back Data if they wanted to. I don't really care if you want to kill Data off, but do so in a way that, I don't know, makes me feel something. Introducing B4 made Data's death meaningless.
Aside from those two things (which you have to admit are pretty major in terms of this movie), I just thought most of the movie was really awkward. The dialogue was terrible. The direction was worse.
And dammit, how hard is it to give Dr. Crusher something to do?!