After a long discussion with my colleague this morning, I have concluded that the Iceland plot line suffers from two main problems. First, it has been salted sporadically on the screen over a year and a half so it's hard to remember who killed whom; and, it's been filmed in a bleak grey-scale that mutes the scenes as well as making the characters all hard to distinguish. That said, I tried to piece the story line together so I could figure out the cast of characters and their actions. Colleague said, "I really don't care. All I care about is that the Viking culture is devouring itself from within. In the case of Iceland it's vengeance. That's all I need to know." Which is kind of sad because those performances are, therefore, wasted and it all could have just as easily been done with a single text-card, a la PowerPoint, "Vikings Take Revenge and Kill Each Other. Sadness." That's hours of screentime down the tubes.
I then noted, for what it's worth, the best story lines are those showing the Viking cultures assimiliating (in equal measures) with other European ones -- Ubbe and Torvi in England and Rollo (momentarily with us) in Frankia.
The sad ones are in Norway (where Ivar's insanity is killing his own kingdom) and in Iceland where the revenge culture is killing their own meagre attempts at survival.
That's a kind of bleak prognosis.