It was a cool movie, mostly because it was about life in old Scandinavia. They did speak a little bit of Old English–it sounds a lot like Icelandic or anyone of the other modern Scandinavian languages. Oddly, Old English didn’t sound much like English.
The actor assisted computer generate animation was on the whole in the “uncanny valley,” not fake enough to enjoy as a cartoon and not real enough to be thoroughly tricked. Lot of moments where the actors seemed creepy.
Ancient myths completely ignore all the rules about how a story is supposed to unfold–things like the hero is not allowed to die, at least not until very late in the movie. The movie patches up a lot of the typical gaps in a poorly recorded, re-told too many times myth. Still, the rules of magic in the movie were inexplicable. Magic gold horns may have passed muster in ancient England, but I think nowadays, we deserve some initial motivation for using magic.