I"ve watched the first two episodes and have quite enjoyed them. I wish I knew more about the Viking period to make a judgement on the accuracy but it does have a certain atmosphere about it so far that would fit Scandinavia in the 8th century.
One thing: the main character uses what he calls a "sun stone" as a navigational tool to find his way west; a problem for early viking sailors I imagine. I did read something in my local paper about some archeologists finding just such a stone, quartz according to the article, in a dig associated with vikings. So they seem to have got that much right.
Generally speaking I have really enjoyed the first two installments. At least the History channel is showing something nominally historical in the "Viking" series, as opposed to the steady stream of "pickers", Pawnshop owners, swamp dwellers and other nonsense.