I went to see this three times and am tempted to go again. I honestly have no complaints about this movie, or the first one for that matter. The scenery is stunning, the acting is spectacular (can we talk about Martin Freeman's expressions?), there is a lot more action than in An Unexpected Journey, and the movie in general is exceptional.
As far as I can tell (I haven't read the book in a long time) they haven't actually taken anything major out of the story. And the things that were added? Well yes please. Most of the added information is apparently from the appendices and Unfinished Tales (am I correct?), which I never read. So for me, the extra information is absolutely wonderful. The added backstory about Sauron/The Necromancer is great, especially since it includes finding out what the heck Gandalf was actually doing all those times he disappeared in the book.
Tauriel is one of my favorite additions to the story. She's downright fantastic with her insane fighting skills, gorgeous wardrobe, sassiness, and ridiculously cool hair. She and Legolas have one of the best scenes in the movie, battling orcs along a riverbank. And Martin Freeman just portrays Bilbo so perfectly, with his odd little movements and... well, excellent acting. Actually, all of the acting is excellent. Everything is awesome.
If I went in to detail about all of the things that thrilled me about this movie, I would never finish writing this. But I do have to talk about Smaug. The animation of Smaug is some of the best I've ever seen. That creature is unreservedly magnificent. He's massive, intimidating, and brought to life with perfection. And with Benedict Cumberbatch's epic voice, it's unforgettable. So if you haven't seen this movie yet and you have the chance to go, GO! You won't regret it.