Did not care for it, but didn't hate it; I would put it at 3/5 stars.
Worst parts included the gaping plot holes, and amnesia (I heard someone yell "Are you kidding!?"), the necessary shot with the American Flag, and watching Harry eat with his mouth open.
Second worst parts included MJ's whining, Tobey's emo hair, Spidey ALWAYS losing his mask in fights, and squirming uncomfortably when Tobey thinks he's Bob's gift to women.
Neutral parts were the dance scene (we had cheering, not booing, in our theater), the scenes with the landlord and Ursula, Topher's role in general (not great, not horrible), and Harry being an idiot and using the damn blade board again.
Decent parts included MJ getting smacked (collective gasp from the audience), Spidey parade, Venom's appearance (as in, how he looked), and emo-Tobey going against Harry at his house.
Good parts included the Sandman's story, the final fight (especially how to deal with Venom), the previews for Pirates 3 and Harry Potter 5 (they look good, GFY), and the scene with MJ and Harry (another collective gasp, but I felt the chemistry between those two a lot more than between her and Tobey the entire time).
I'd see a fourth, but I felt this was pretty weak, and I would only go if friends wanted to go. And it makes me think once again that Peter Parker = Charlie Brown. Anything bad that can happen, WILL happen. Not as bad as Matrix 3, not by a long shot, but not as good as LotR 3 either, again by a long shot.