Well, I fear that my rating of this does not reflect my opinion of it; that is to say that I didn't really care for it that much.
On the other hand, I think it's probably pretty well written. I like the flavor of Norse mythology, but it was no more than a flavor, and overall, that ended up just being a misdirection. That may well be the reason that I didn't care for it as much as I expected to.
The characters were well defined and consistent. And the plot was pretty good. It was nice to see one of the early important characters show up at the end, as opposed to being totally forgotten. Actually, it may in fact be worthy of an entire series after all…