Review is based solely on the story mode, I haven't played Saga mode but I don't know if I want to.
1. Fun first half, second half gets very repetitive very fast.
When everything was new, it felt great to explore and craft... but once you got a feel for the game, you realize how repetitive and tedious it is. As your character gets stronger, enemies become nuisances and dungeons/enemy camps become chores.
2. Unnecessarily big maps.
There's 4 biomes in the game spread out randomly according to your generation but they always just have the same few things. If you've seen the biomes on your starting island, you've seen the biomes on the far edge of the map, making exploration beyond the 4 biomes you found earliest to be redundant. There's also nothing to do while sailing beyond dodging the occasional obstacles and stupid sea serpent you can't even attack. It's honestly god-awful spending close to 15 minutes sailing and dodging other islands just to get to the far off quest mark.
3. Lack of build diversity
The biggest sin in my opinion. With the way runes stack and having different weapons and elements in the game, it opened up potential to so much they can do with the gameplay... but in the end you're just going to either stack the naked rune together (give damage if you're not wearing armor) or the fenrir runes together (give 2x damage if you're below 50% health) in late game... and all you're doing is mostly just spamming attack. Other runes pale heavily in comparison.
THE SKILLS ARE USELESS.
They're slow and doesn't do as much damage as your regular attacks when you have the level 1 berserk stacked up.
And if you're like me, you'll realize only the bow is really worth investing into... other weapons put you in harm's way without much option of self-preservation (that the bow doesn't have) and doesn't deal nearly as much damage to make up for it as the bow can oneshot regular enemies anyway. An exception is the axe for late game bosses but all it does is save you a bit of time.
4. Constant Crashes
I don't know if it's just me, but I've had the game crash several times on several occasions. To the point that, get this, it saved my first save in a spot where I just crash when loading in... (outside some dungeon) and I had to redo my game. TBH it's not that big of a deal... WHEN THE AUTOSAVE WORKS. But sometimes I get a game crash and when I load back in, the last autosave was maybe 30 minutes to 1 hour prior to the crash and that's just disheartening.
I had high hopes for this game when I started, when it's at its peak, the game's fun and simple... eventually, I just end up feeling like it's not worth to even play to completion. I bought this on sale and it was still a bit disappointing.