I went in with fairly low expectations, since my parents had a lot of complaints about the movie (although they were nice enough not to actually spoil anything).
So...with that outlook going in I had fun. It wasn't good, but it was fun. But I agree with a lot of people's complaints about the movie.
I must confess that I found parts of the barrel scene rather amusing, although the overall set-up and execution was silly and often the special effects just looked off. Bomber bowling over orcs was funny, at least.
Mirkwood bugs me. Mostly because they cut out a bunch of scenes from Mirkwood so they could add in a bunch of extraneous stuff to the movie. Really? You're trying so hard to spread one book out over three movies and you cut stuff out?? Boggles the mind.
I'm of two minds about the Scenes with Smaug. One the one hand, the fact that the dwarves didn't get immediately killed is pretty silly. On the other hand, it's kind of nice that they at least tried to fight him in the movie. In the books I was always dissapointed that the dwarves went through all those troubles and overcame so many obstacles to get to the dragon and then didn't do anything at all about him. They shouldn't have succeeded, no, but it's nice that they at least tried.