Lords of the North by Bernard Cornwell has Vikings in it, so it is automatically brilliant. Also, Cornwell is one of my favourite authors.
One thing that characterizes Cornwell's writing is a tendency to end a scene or chapter with a snappy short sentence. For example 'The gods were not happy.' Sometimes it's a cliffhanger, sometimes it's foreshadowing and sometimes it adds drama. It serves to drive the story forward and makes his books hard to put down!
This is written in first person POV. It seems like I'm reading a lot that's in the first person lately. I don't know if that's coincidence or a trend. In this case, the main character is an old man telling the story of his youth. The voice is very strong. It's confident and self-assured, and well suited to the character. What is different to many first person narrator's is that there isn't that much internal monologue or exposition. The story is largely told through scenes with solid description and great action. What internal monologue there is, is very effectively used to show character.
I really enjoyed this and Cornwell has a style of writing that I particularly enjoy.