Written last month, I apologize for the late posting.
Spoilers beware!
(Also, please be aware that gender and race will be discussed, as per my usual shtick re: reviews. Just because Tolkien is the father of my work doesn't mean I will suspend my expectations when it comes to storytelling.)
This film, I believe, outstrips its predecessor by a fair margin.
There, I said it. Despite having been a fan of Tolkien's work since I was less an hobbit-sized myself, and despite having clear memories of being incredibly angry about the alterations made in the original movie trilogy (despite them being, over all, very minor), I think this movie is one of the best Tolkien adaptations made so far, falling only short to Return of the King.
Desolation gives us glimpses into the parts of Middle-Earth's history that The Hobbit in its novel form cannot, by virtue of the medium. This is the reason that the Hobbit movies are to be a trilogy, and it is wonderful to see it at last brought to life on the silver screen. As a fan of the story-behind-the-story, who knows going in that Sauron and the Necromancer are one and the same, and subscribes to the theory that the Arkenstone is the Silmaril cast with Maedhros into the earth, I got to see more of Middle-Earth than I could have ever dreamed.