It really is a extraordinary series. Unique, engaging, badass, with a solid comfortable blend of drama, good quality humour, amazing action/war scenes and true real life gritty realism. You might think the plot would just be the usual revenge story, but it turns out to be a lot more than that, with plenty other directions being involved. It's pleasantly unexpected. The art, of course, is very well drawn, detailed and overall great.
The characters are also remarkable. They are quite real, with great interactions and very complex in many ways - not just the usual black and white. Also, they can get dirty, they can be affected by the stresses and brutality of daily life, or they can actually die. No more perfect unhindered hair or porcelain skin and clothes as emphasized in everything else, which just adds to the authentic intensity. In general you will definitely have at least one genuinely favoured character (Or one you love to hate). And for the ladies, if it matters: there are some really good looking men!
It really stands out against SO MANY other mangas out there. In retrospect, if you are a fan of the "Song of Ice and Fire" novel series by George R.R Martin (Like I am) you would likely enjoy this manga. And overall, works for an older audience who might feel weary/uninterested with other typical mangas and their themes.
And yes, after all the Viking travels, battles, great dramatic moments, and the rise and fall of certain princes/kings who are fighting amongst one another, there is a Farmland/slavery bit that has offput some people (And I can understand why, it can feel slow, considering how long it takes for updates to occur. I was lucky enough to not have to wait at that time since I got into the series only a couple months ago, and just read through easily). But one has to comprehend the importance of journey, realization and personal will, instead of everything that are just handed over to characters or having the story depend only on constant typical action scenes. Everything in this series is so much more deeper and meaningful. The Farm chapters also offer a whole new other buildup for the next dramatic segments, as is tension of a ruler desiring to come in and take over everything through force, and there are other inner conflicts growing within the dwelling. Besides, during the farm era segment, you also get inbetween chapters that follow another main character who is going through the process/stress of being a rising and conquering king.
The only downside is sometimes the chapter updates can be a tad bit of a torture to wait, with cliffhangers of course existing in a healthy amount. But, considering the intricacy of the whole thing, I reckon it is better to get slower updates in order to obtain quality instead of faster updates and have everything rushed or poorly done.
It's not historically perfect of course (I mean, it's rare that anything is anyhow) but it is nevertheless quite satisfactory - it still does it's job. I'm Viking descent myself afterall, so it pleases me well enough. There are a lot more worse books, movies and whatnots out there that totally butcher history.
Anyhoo, definitely a recommended read. It's a gem, and a top personal favourite.