Many of my criticisms of An Unexpected Journey apply here too: over-length, unnecessary action sequences, padding the story out with extra bits that don’t add enough, and sticking too closely to the formula established in the previous trilogy. There are also some more specific criticisms to be made: the opening scene lacks ‘oomph’; the ending is weak, lacking even a semblance of finality, let alone resolution; the Kili-gets-injured-and-winds-up-in-a-love-triangle subplot is entirely superfluous and irritating, especially since the two other members of the triangle (Legolas and a female elf created for the movie and played by Kate from Lost) aren’t supposed to be in the movie at all; in the motion-captured-character-redeems-movie’s-final-act stakes, Smaug is no Gollum; the entire Lonely Mountain sequence is muddled; and Thranduil’s arseholishness, with no real redeeming features, quickly grates.
Having said all that, there are still some fairly enjoyable parts (the barrel sequence, for instance), and all the usual elements worthy of praise in a Peter Jackson Middle-Earth movie (action, visuals, music, casting, etc.) are still there too. As for acting, Orlando Bloom continues to think that squinting is the sole form of emoting available to him, Stephen Fry overdoes it a bit as the Master of Laketown, Sir Ian McKellen is solid as ever but seems to be overusing the move-bags-under-one’s-eyes-to-indicate-drama technique, and everyone else is fine.