It better be damn good.
Oh, it most definately is. It's an incredible piece of art, that has more jaw-dropping moments that I could count. However, you 1) have to be able to completely suspend your disbelief (physical laws such as gravity do not apply in this world), and 2) have to know the story and characters from the game. People not familiar with the game should probably skip it, unless they really enjoy mindless action.
My understanding is that it is still due to be released in January, and I've seen quite a few ads in gaming (and other) magazines stating such. Methinks Amazon just has their date wrong.