I played Valheim with two other friends and it was one of the best co-op experiences I had. Right from the beginning it delivered on the Viking feel in the gameplay. One thing I want to mention is how the wooden building blocks in combination with the smoke system and the way stability works, make you automatically build houses that resemble traditional Viking longhouses.
Especially the first two bosses felt really well designed with different move sets and general game feel. Let's not talk about the swamp boss, but the final two bosses felt weak. The later regions like the mountains and plains also seemed almost too straightforward in the end. It was seldom worth upgrading the current armour since the next material would devalue it on level 1.
I really liked that they reused older materials (iron) in the plains biom. I felt all systems got their due share to be used. Farming for examle was always important for good fold, but peaked again in the plains when you needed a farming outpost to harvest flax and barley for end game armor and food.

All in all the game already is worth its price. I'm looking forward to the upcoming updates and will probably play it again in one or two years!