We know they didn't live in hierarchial societies at least. Social classes existed but they weren't like the show portrays them. I can't comment on that quote but I think there are several works of fiction who give off a better researched picture (the vikings didn't write anything down with words, but the priests who tried to christen Scandinavia did, and other cultures they were in contact with, such as the Byzantines, were literate). There's an awesome, awesome book called The Long Ships written by Frans G. Bengtsson, for instance. I can't recommend it highly enough if you haven't read it. It's two books in its original form but I think they are published as an anthology nowadays. It's one of the cornerstones of contemporary Swedish literature.
