I played Valheim about an hour and this game is fantastic!
Yes, it is an Alpha and there are many things that must be implemented, but the game really has potential!
The building menu (opened with the hammer) needs a complete rework (bad usability, not easy to handle).
Show a larger window with multiple rows of icons that can be controlled with the mouse.
You can (should) keep the tabs in this window.
It is not easy to build walls on top of walls (even placing wall roofs on the edges is really hard). You need a larger "snap area" where the elements easily snap together (easier building).
It should be possible to look up to add a second row of walls.
Some more ways to fill up my health would be helpful (especially at the beginning).
Maybe you add fishing, this would be an excellent way to get food for beginners (right after the start). If cause players have co craft a fishing rod and collect some worms.
It also would be good to be able to collect berries that can be eaten.
Please add an auto-heal (slow healing like 2 minutes in real time until the health bar is full again).
I have no bed yet but please allow sleeping and fill up the health while sleeping.
The inventory and the quick access bar (accessible with the keys 1, 2, and so on) should be separated.
In my inventory I saw that there are multiple piles of items that are not full, so a button "Stack items" that stacks all piles of the same item would be useful. I had for example 4 stacks of wood with 3, 12, 6 and 4 wood (could be stacked to 2 piles).
Most important: add some basic tutorials , they would be excellent for beginners.