I won't say I didn't have any fun playing Valheim, but I had far more negative experiences than positive ones, and definitely not by playing the default intended experience. If you're considering getting the game, be forewarned that you're probably going to want to install at least a few mods for a less tedious and annoying experience.
The controls are janky and annoying; any shrub, rock or lump in the ground can and will obstruct your movement. Like Bethesda games, bumping into a vertical surface will intercept your jump height and prevent you from climbing small ledges. 45 degree stairs are especially janky, making you hop up them instead of just walking like a normal person. If you're overweight and trying to haul some stuff upstairs, well good luck, you're literally too slow to climb them.
The combat is mediocre at best, and awful at worst. It feels like they were trying to emulate Soulslike/Monster Hunter combat, but it takes all the wrong notes. your stamina recovery is abysmal; while you can increase your maxima stamina as you progress, you have limited avenues of scaling stamina regeneration as you go, and without them, a large stamina pool can take a whole minute to fully recover. your hits can easily miss an enemy too far above or beneath you, there's a massive amount of knockback that sends enemies flying out of your hit range, but also can send you careening into another enemy's hit.
You're expected to learn to parry and block attacks, but most 'level appropriate' enemies will easily chip off a good 30% of your health in one hit, your healing is limited by 2 minute cooldowns (healing potions themselves take a few real time hours to ferment), and dying is a heavy penalty; Even on casual difficulty you drop everything that wasn't equipped. If you died while swimming, your weapon is sheathed so you drop that too. If you died on another island before you could set up a portal, now you have to make another boat to sail back there again. If your tombstone is surrounded by enemies way out of your league, you may as well give up on recovering your stuff and grind a few hours to replace that loadout.
Your inventory is tiny, and your armour and trinket take up inventory space even when worn, permanently exacerbating your inventory constraints. Your weight limit is pathetic, and many items are heavy. Unless you make a dedicated effort to ignore and throw stuff away, you will fill up with all manner of junk either from weight or size constraints barely a few minutes out of your base. Your basic storage chests are equally small. There's no upgrade for at least another few hours, there's no crafting from storage, no sorting or searching function.
The game has you build upgrade buildings adjacent to a crafting station to unlock more features as you go, and they are extremely finnicky about the placement. Not too far, not out of line of sight, on a wall only, not allowed to plant them down if they won't affect the crafting station— They're unnecessarily difficult to place, and to a degree, you have to plan your work area around them. Later zones add more and more crafting stations with limited utility that could have easily been folded into the existing ones, and it seems to be a deliberate effort to clutter your base up with even more crap.
Grinding for materials is a slog. Its a lot of tedious rock and tree slapping for a drop in the ocean of what you will need, that as I mentioned before, are heavy and necessitate numerous trips to bring back to base. Just like in combat, you will run out of stamina while mining or chopping trees and have to sit around waiting for it to recover. You can make a cart to expedite the moving process, of course, but that also requires a lot of terraforming to pave the way for the cart, only for that path to cease to be useful once you've dug up the entire mineral vein.
Content is spread out far and wide, necessitating a lot of travelling without anything to do in between. Sailing is a novel mechanic, but underdeveloped, a beautiful but ultimately empty expanse you are forced to cross just to set up a portal on the next landmass you reach so you don't have to do it again.
In summary, Valheim is the indie version of a Bethesda game, terribly broken, but not something most mods can fix. But while Bethesda games are mindlessly easy and droll, Valheim is a frustrating exercise in frustration and artificial difficulty.
