Artistically, there are a number of things I'm intrigued to see.
Firstly, how Jackson reconciles the "stylistic" differences between The Hobbit and Lord of the Rings. Recently re-reading the former, I was struck by how different trolls and elves are portrayed compared with their LOTR versions.
Secondly, it's clear from the trailers, casting, etc that Jackson is going to incorporate a lot of stuff going on at the time of The Hobbit but which is not mention in that book, only in the appendices of LOTR and The Quest of Erebor in Unfinished Tales.
At least on this second point, it seems Jackson's adaptation is going to be more "what we know about the story from all of Tolkien's writings" than just "what's in the book The Hobbit".