I'm adoring this game. It's been my focus of play since it launched on Xbox Gamepass.
The only major thing I've noticed during my playthrough that they need to change is to clearly communicate what exactly has been unlocked from new material pickups.
It is super satisfying to pick up that first smelted iron bar and see the "notifications" of everything being unlocked. But those "notifications" are only on the screen for 5 seconds or less and once they fade away you are left wondering what exactly all of those 30+ unlocks you saw were. The notification is not enough to help out the player, there needs to be something else to communicate new build pieces or crafting recipes.
In the Build menu and Workbench/Forge menus, there needs to be some way to indicate to the player what "New Craft-ables" or "New Build-ables" are available or have just been unlocked. Something that persists until you interact with it.
It's been fine up to this point, but the worst occurrence of this was when I beat Yagluth yesterday. Although I picked up his boss drop, the speed of the notification and my focus being on my low health (and watching for Fulings or Deathsquitos), I did not see what was unlocked by its pickup. I spent an hour+ around around the edge of the Mistlands hoping to unlock something to interact with the boss drop, but I had already unlocked it! If this feature was implemented it would have been much clearer for me and would be clearer for any new player too.
Source: https://www.reddit.com/r/valheim/comments/12oeg24/feedback_clearer_unlocks/