Alright, finally saw it, really did not like. It's not exactly bad, but the divergences ruin things.
Main objections:
Elves: For fucks sake Jackson, don't you at all get the idea of the Elves being jolly pagan revelers? They sing and party in the book! Multiple times! Bilbo only escapes because the guards got drunk on the King's wine! This image of the elves as ethereal and refined beings isn't entirely out of picture, but it is definitely wrong as portrayed in the film.
Romance: Ugh, fucking Hollywood. The Hobbit is a deconstructive adventure tale, there is no romance. Nothing else to say on that.
Smaug: The entire idea and purpose of Smaug is ruined by the film. You do not fight Smaug. Smaug completely destroyed two of the most powerful kingdoms in the world in one day, on a whim, because he wanted gold that he has absolutely no use for. The only survivors were the people who ran and didn't look back. Bilbo survives an encounter with Smaug, and this is because, and only because, he possesses the One Ring. Even then, he's still in great danger of being found the entire time. Bilbo should have been roasted the moment he removed the Ring, and the Dwarfs should have been roasted the moment they entered Erebor with Smaug present. Smaug is not a dragon that gets slain by adventurers. He is vastly old, vastly evil, and vastly powerful. He dies as a result of pridefully displaying his only weakness.
I did like the acting, though. Had it only been more like Riddles In The Dark and less like an extended battle scene, it would have been great. I will say I appreciated the visual pun of the company temporally literally making him Smaug the Golden, as stupid as the setup was. "Scales like tenfold shields" being turned to "scales like iron" irked me, as well as generally splitting up the lines of his speech over ten minutes of fighting.
Beorn: This is partially my father's bias rubbing off on me (Beorn is his favorite character in any book, period), but Beorn was horrifically wrong. Beorn's demeanor is "jovial and wild", not "racist jackass". He is supposed to be someone who is rough and unpredictable, but mostly benevolent- i.e., an analogue of the natural world he is immersed in. And to make it even worse, Jackson missed out on one of the few opportunities for a fully justified action scene. Why no Beorn v. Warg pack, Jackson? That happened in the Hobbit, even if it was unseen.