Saw this more than two weeks ago, but the holidays and the end of the semester have had me too busy and/or exhausted to review until now.
Overall, I liked it more than the reviews of my trusted critics suggested that I would. The songs were fine, though I was a little miffed they didn't have the goblin song (loved it in the Rankin Bass animated version). My only serious complaint was that it took a while to get going. However, the more I think about it, the less that bothers me as a number of the fantasy/sci-fi books I've come to enjoy have the same thing (Steve Erikson's Malazan series and Peter Hamilton's books). The casting was spot-on. Martin Freeman is the ideal Bilbo, and although he is a little too dashing, Richard Armitage was good as Thorin. I can't remember who played each dwarf, but those who performed Balin, Dwalin, and Bofur were my favorites (Bofur's scene with Bilbo was particularly well-done). The returning cast members were great, especially Andy Serkis and Ian McKellen.
To be honest, I think the series will only improve from here. Given the (perhaps unwise) decision to make this into a trilogy, I figured this would end up being the weakest while the next two would have the most meat. Still a solid start.