This show is irreverent. You have to Love dry comedy. There are sad and depressing moments (the end), nonetheless, as this was made by a bunch of Norwegians.
Because there exists other Viking oriented shows, which this one was is based on to poke fun of, and this one is created by Norwegian writers and actors, lending a very dry sense of humor, an ordinary person from the United States might watch the show and be offended.
But, they are simply confused. It does not make an effort to be historically accurate - in fact - some more funny moments come from these slips. It is extremely gory and depicts the nature of the Vikings without any romance. It is like watching the Sopranos. I don't think anyone making the show was trying to glorify the heritage of the Vikings.
If you are from Northern Europe, and you take a 23andMe test, you will likely find genes originating from the original Vikings --- Denmark (not Norway-- that's where they landed). A lotttta lot of us have Viking roots... meaning we were not necessarily rapers and pillagers. We were raped and pillaged.
I love this show.