After downloading the 500mb+ demo from Xbox Live Marketplace, I decided to give the demo a good thrashing. Unfortunately, as is the usual case with movie to game conversions, this game bites for quite a few reasons.
Firstly, the graphics do not scream next-gen more like Playstation 2 graphics, and let's face it, if you have an Xbox 360 you want your games to look hot.
Also, it plays like a very generic platformer. Mainly hack, slash and jump. This is all done from a distant 3rd person perspective, though it does zoom in during combat sequences under certain conditions. (i.e. Mainly to show off a fatal attack.) Voice acting gets irritating quickly as well, though I think the actual actors from the upcoming movie voice their characters.
If you're looking for a next-gen game, or at least one that doesn't look like it belongs on your Playstation 2, I would suggest King Kong for Xbox 360… and I'm not even a big fan of King Kong! Or better yet if you have access to Xbox Live Marketplace, and are not too fussed on wasting your broadband allowance for the month, you can download the Eragon demo and play it for yourself.
I hope the movie is good anyhow, but we shall also have to see about that!