It's big. Let's compare it to the
Tomb of Beasts, PHB, and
Tal'Dorei Campaign Setting:
View attachment 95935
Now, a lot of that is the thicker pagestock Kobold Press uses. But it's still 461-pages of text, with 400-pages being world lore.
There's some online support for the setting:
https://koboldpress.com/midgard/
On that site you can see each region gets a blurb.
Also, check out this little map program to get a look at the world:
http://midgardmap.koboldpress.com/
You can see there's a definite "Eurasia and North Africa" vibe of the world. But there's a LOT going on in the world and a vast amount of information in the book. Which is extra dense with the limited art of a 3rd Party Publisher.
I've been reading it for two weeks and still feel like I've barely skimmed the surface of the world.
In terms of comparison with Golarion and Pathfinder's book, the world seems smaller. It's a less expansive world. Both have some real world analogues, especially in Egypt. But Midgard tends to twist its more, adding non-human races to the mix and more active gods. And there's a focus on Norse mythology, with the Northlands being a key aspect of the setting, especially their gods (Thor, Loki, Woden, etc). Vikings are a thing, but these might also be raider dwarves and ravenfolk have a key role in the North (along with Trollkin). The magic and other species seem much more a part of the setting and it's less "Revolutionary France land... but with magic" or "Horror Romania Land... but with elves and half-orcs in the cities". Which makes sense as the world was slowly designed over a number of years, and with constant feedback from fans and backers of the Open Design project. (Basically, everyone could pitch ideas and concepts, with people voting on the best ideas.) Magic is much more of an impact on the world, with clockwork mages and ley lines crossing the world. But the magic also has a tone beyond "these are the game rules, which are the physics of the setting."