Really short - took me 9 hours and I really was dawdling and repeated quite a few levels. But it is fun which is why I repeated some levels. The storyline's good but it did feel like I was playing a sequel ie. I should know certain things about the past already. If you don't worry too much about the strange scandinavian names for places and characters then you'll be fine. But if you're like me and need to know what everything means and where you heard that word before in the story then it'll frustrate you a little.
It's amazing how you can do so many different actions with just a few buttons.
The cut scenes were great visually but the sound quality was really bad and fuzzy (maybe my ds).