It certainly is un-nordic. I think it would have been cooler, or at least, more in line with my tastes, if he was more of an Achilles figure .
It is, in my opinion, more along the lines of the old epics and sagas. It is not so much about redemption (ugh) and more with the consequences of wrath and its consequences.
There are serious traces of this in the story. Askeladd's story is driven by rage. As a character he is moved by a misanthropy fueled by his hate and contempt of the Nords.
Rage and wrath is the main driver of this story. Thorkell is an embodiment of this war lust/battle rage: a barbaric reveler. Bjorn is a strange example: he provokes in himself a chemical rage to go into battle. Thorfinn is, like Askeladd, fueled by a certain hate and contempt of men, having lived among Askeladd's man, and more importantly, hate for his father's killer. Canute also came to embrace his hate for the human condition and his rage against the heaven.
Thorfinn is a deviation in that he is... burned out. His hate has petered out with Askeladd's demise. Which I guess is still an exploration of the consequence of his own single-minded rage.
What drives Thorfinn now?
He wants to escape this world filled with hate and rage. Vinland I guess is that escape.
I'm not saying that he is awful as a character. I think he is in fact fascinating as a character. I'm just not too hot on the implications.