As I watched the teaser, I noticed there's going to be significant additions and changes to Bilbo's tale in the second installment of the trilogy, and...I couldn't care in the slightest!
As long as the movie maintains the key points of the book, which at first glance it seems to do, I will be thrilled to have more action and a little more depth. I actually like the idea of seeing the Elves' side of the story, in particular, including Legolas, the Prince of Mirkwood. Plus, Evangeline Lilly as Tauriel, head of the Elven guard, should make for an interesting heroine.
A few things to note in the teaser: Beorn's giant bear form (I assume), Radagast, Gandalf about to storm the necromancer's keep, spiders, barrels, Azog, Bard the Bowman, and, of course, Smaug. It's evident, as was rumored, that Vermithrax Pejorative from the movie Dragonslayer was used as inspiration. I don't know how far the second movie will go, but it would appear we can expect the initial conversation between Bilbo and Smaug. I'm unsure if we should expect the culmination of that part of the story, though, given the title, that might be the case.
That said, I can speculate the third and final movie will be based around the Battle of the Five Armies and the journey home, meaning the Desolation of Smaug will have a lot of action. A lot.