I enjoyed this film a lot and glad I went to see it on the big screen. It's a great addition to Robert Eggers' filmography, though I'm absolutely certain he is capable of much greater films and this one falls a little short of being a masterpiece.
I'm actually fairly confused as to why so many audience reviews have been mixed at best - some of the complaints I've seen are that the actors look too clean and hygienic (my understanding is that the Viking period Norse were fairly hygienic compared to what we assume about medieval peoples). I heard quite a few people in the auditorium laughing at certain points during the film - only one instance of which I understand why it was funny; the other moments of laughter seemed almost like uncomfortable laughter or being unable to take the dialogue seriously at its face value within context.
There were some pacing issues in the second half of the film, but not major.
The costuming and scene design are the best I've seen in a period piece in however long I can remember - and immeasurably more authentic and "accurate" than any other Viking period-themed film or TV show. There are references to archeological finds and studies throughout the film - treasure hoard objects, filed teeth, and a prominent warrior who's DNA was recently found to be female.
The film doesn't pull any punches - it doesn't make the Vikings (as in the actual pirates/raiders) look even remotely morally acceptable or relatable to modern audiences. It shows slavery, implies rape, and mass murder, all without feeling contrived, glorified, or forced. It feels unapologetic, as if Eggers is trying to correct the popular depiction of the Viking period that's cropped up in media over the last 20 or 30 years.
The film also shines in its depiction and presentation of Norse mythological themes - delivered through visions, drug use, and general mysticism and superstition. Lots of strange unexplained events happen that could be explained away in multiple ways - but there's no need to, because these people probably saw it at face value.
My final thoughts are that although funding and casting would have been different, the storyline may have benefited much more from being produced as a couple of films or a short TV series, mostly due to the pacing, but I think that would have changed the budget too much and Eggers' presentation and direction might not have been delivered as properly.