One of the search terms that found my blog was "Lagertha coiffure," so I think people are fascinated by the haircuts.
The helmets and shiny West Saxon armour did drive me a little mad -- although they're still less ridiculous than the armour Ragnar wears in S3, which appears to be made out of some kind of braided leather. I get why they're doing it, which is to create a uniform, distinct appearance among the troops of the various factions. This was a thing in Game of Thrones as well, where the show invented these weird uniforms for each nation so they'd be easier to tell apart visually.
(I actually really struggled with this in Band of Brothers -- a bunch of skinny white guys, all covered with dirt and all wearing the same clothes and haircut, can be hard to tell apart for the first few episodes until you've got to know them. There are a handful of easily recognisable actors and then everyone else is just some guy.)
But yes, the history is just ... I can't believe that people are objecting to the helmets but not stopping every five minutes to shout "WHEN IS THIS SET?! Horik died in 854, Aelle didn't become king until some time in the 860s, Rollo wasn't born until the 840s, and the siege of Paris was in the 840s but the Lindisfarne raid was in the 790s. Alfred the Great was born in 849, but anyway Judith wasn't his mother (although she was married to his father) and also she was 12 and not from England. So the helmets seem like a small matter by comparison.
And why do they say AY-thel-wulf but ATH-el-stan? It's ATH-el-wulf.
And yet I really enjoy this show. Such lovely cinematography, and Gustaf Skarsgard is fun. I like the kid that plays Bjorn, although I miss his authentically stupid 11th-century haircut.
The thing that really jarred me that I should have noticed before someone pointed it out was the towering mountains and rocky fjords of, er, southern Denmark.