I've been waiting for someone to make a good series about the vikings. I'm from Norway myself, and I'm naturally interested in our history. I've only seen two episodes so far, but I have to say - it really looks promising. The surroundings and nature in the two first episodes is exactly how it looks in "Vestlandet", the western parts of Norway. Stunnings fjords with waterfalls cascading down the sides. It really looks authentic.
The acting is mostly top notch, a few short scenes aren't that great but it's hardly mentionable. It seems like in the beginning, people are speaking an incomprehensible Norse/English mix, and then they continue speaking a modern English. It's pretty clever actually. Fun fact: When the Vikings invaded the British isles they could understand each other's languages.
The story itself is really exciting, and I just want to watch more.. I can hardly wait for the next episode to be released.
I don't know so much about the Ragnar Lodbrok character, but Rollo (Gangarolf) is a very famous character in the Norse sagas.
I highly recommend this show, and I really hope they continue making this for several seasons.