This is a very mixed movie. Some parts are great (most of Laketown for example - I love the Elizabethan London + canals feel to it). Jackson did a great
job with Bard too. Quite frankly, I think that he did better with Bard than Tolkien did, because IIRC Bard just shows up out of nowhere as a Deus Ex Machina to kill Smaug, and only gets fleshed out later.
Thorin continues to be amazing, as does Bilbo. Smaug was also very well-done, though I'd have preferred of more of Cumberbatch's voice came in through Smaug. There were a few bits where it still felt like Cumberbatch, but for the most part if felt generically dragon. I did have some flashbacks to the Draigoch
fight in LOTRO throughout though in that gold was heavily involved, as well as a smug snake of a dragon taunting the heroes - which makes sense since Draigoch was heavily based on Smaug.
The Dol Guldur sequences were also incredibly well-done. I liked the Sauron came across as a credible threat again, in a way that he hasn't since Fellowship of the Ring (though zooming the Russian Dolls sequence got a bit laughable). Shape-shifting shadow of doom is definitely scarier than an eyeball lighthouse.
However, I completely
agree on the pre-elf bits in Mirkwood and with Beorn. They could have cut off a huge part of the barrel sequence to expand it and really establish the otherworldly feel of the place. I suppose that the spider fight wasn't as necessary this time around since Bilbo had already found his courage in battle, but I'd have liked to see him invisibly sneaking around and taunting them as he killed them.
Kili and Tauriel just got old fast. I prefer the quick-witted-but-naive Kili from the first movie rather than the lovestruck Kili from this one (well, at least post-Tauriel). Also, dick jokes? Really?
However, these complaints completely pale to that incredibly, insanely, utterly stupid action sequence with Smaug at the end. I'll grant you that getting to the guard tower was intelligent, and getting to the forges made a great deal of sense as well (though they should have still been charbroiled when Smaug lit them). However, everything from that point on was downright cartoonish. Bombur working the bellows by riding up and down a chain? Huge rivers of molten gold, with Thorin sailing it in a wheelbarrow?!
And worse, given how he was running with it, this was his plan!? And the culmination was a not-before-established mold for a giant dwarf statue that was solid enough to stand for several minutes but molten enough to completely pool over the bottom of the room? And it was utterly pointless because Smaug shook off all of the gold anyway at the end?
Ugh. It doesn't ruin the movie for me, but it was the weakest point in arguably the entire saga. Second at absolute best (the skull cascade in Return of the King is the only other contender).