Its entertaining and worth a watch. Its not perfect when it comes to accuracy but its not the worst either. I dont like how they killed off all the real Viking looking guys in the first two seasons just to keep around people like Erlendur, but then again they are more interested in telling a story than actually giving an accurate portrayal. I also think they focus too much on England, and that although the plot is decent, it could be better and at times they throw in dumb zhit like the Chinese slave and her getting Ragnar hooked on heroin which was a completely pointless filler arc they had this last season.
Im hoping the next season they get back to being Vikings and end up raping the zhit out of England.