First, the good: The dragon was impressive.
For the rest, Tolkien’s story collapsed under the weight of Peter Jackson’s treatment. Nothing from the book made it into the movie unmangled. The changes in the first movie strengthened Bilbo’s character, and on balance I liked them. Here almost all the changes are for the worse. The wonderful scene in which the dwarves arrive at Beorn’s door a couple at a time is gone, replaced by Beorn in bear form pursuing them into the house. There’s a love triangle that was apparently added just to include a female character and let Orlando Bloom play Legolas again. And there are orcs everywhere, even in Laketown.
One point I’ll grant is that Bard’s character is better fleshed out; in the book we’re barely introduced to him before he kills the dragon. Here he’s part Han Solo, part Robin Hood, and he has a family.
I’d hoped that Jackson would do something good with Gandalf’s expedition to Dol Guldur, which is mentioned but not presented in The Hobbit. Sauron makes an impressive appearance, but in the end it’s more of the recipe of adding orcs to everything.
Many parts of the book are problematic in a movie for adults, but there could have been better fixes. The dwarves’ escape in barrels always bothered me, because they should have suffocated if the barrels were watertight. In the movie they’re open, so they should make useless boats, especially in rushing water.
I’m not at all impressed.