Just got back about an hour ago, what a great movie. I'll give a spoiler free review, not that there is any if you've read it.
-Better than the first one. I'm a big fan of the Fellowship, and was of the Unexpected Journey because of their care free vibes. But this movie topped the first for me.
-More action, the movie begins with them on the run from orcs and that chase basically lasts for 75% of the movie. Does a good job of throwing things from the book in there so it doesn't all seem like one big chase.
-More orcs. As I said, they spend a lot of time on the run from Azog and his cronies. The CGI is noticeable, but you forget about it quickly.
-Legolas!!! Loved him in the LOTR, and even though he wasn't in the book, cool to see him here. He has a bit of a background love triangle going on with an elven girl and Kili. PLus he kicks some orc ass.
Look for the barrel scene. So great.