I've watched 3 episodes now and this show is terrible. None of the characters are likeable. I know they are supposed to be bad guys, but it's possible to make bad guys likeable (see Spartacus). The main character keeps talking in a creepy quiet voice and never displays any emotion - he just does a creepy smile all the time. Even when he talks to the Earl he keeps smiling weirdly and I expect the Earl to shout at him for being disrespectful.
The Early is also very one note, he just does 1 facial expression and talks with the same serious tone all the time. There are no interesting plot "hooks" like in GOT and Spartacus.
The first clash between the vikings and the English was nonsensical - the vikings are clearly warriors who've come to steal and kill more (after what they know went down at the monastery), so why did they go up to them and try trick them into coming with them? How did they actually expect to communicate with them when none of them spoke their language? And how did Ragnar already understand so much English when he'd just spoken with the priest a few times? It didn't show him getting any lessons, and it was way too soon after he met him to learn such good English anyway.
The priest speaks way too fluent Danish or whatever, they should have made him speak more simply when he was with them so it would be more realistic. He hasn't made a single grammatical mistake or asked them for a word in Danish.
What was up with Ragnar asking him for a threesome? It made no sense, he'd just met the guy and he was his slave. And if this is supposed to be something not unusual in Viking culture, then why wasn't he having 3-ways with his wife and his mate? She rebuffed him in the first episode but then is up for a threesome with a complete stranger.
The best thing about the show is the song in the beginning. No other shows to watch at the moment though.