This is a gem of a game. Bravo to Ember Lab!
Things I liked:
* Great story with compelling characters (made me cry a couple times, especially the first arc)
* Adorable as heck
* Lovely and appropriate music
* Excellent voice acting ("Aw! Thank you~")
* Beautiful aesthetics, both in its corrupted and uncorrupted layers of paint
* Good progression system with lots of fun abilities, although I do wish I had enough upgrade currency to unlock everything by the end
* Good boss design with the exception of the last two bosses, which were designed by a chimpanzee
* Exploration that was actually enjoyable for a change, complete with a map that can show the locations of collected items
* Great animations and attention to detail
* Stable. I didn't encounter a single crash or graphical glitch.
* Really fast load times. ~2 seconds on an ancient 2.5" HDD.
* Fun combat, most of the time
The only meaningful issue I have with the game is that once you start to push the combat to its limit, you will almost certainly find yourself battling with the controls. It is a relatively challenging game on the default difficulty too, so this can result in some very frustrating deaths.
Full list of cons:
* Abilities often use the same buttons, so I found myself frequently triggering unwanted attacks. For example, if you hit A, hit left trigger, and then hit right trigger, you'll jump and fire an arrow. But if you hit left trigger first, or have left trigger even slightly depressed from the last arrow you fired, you'll do a heavy downward attack instead. There are a handful of overlapping combos like this that are easy to trigger by accident.
* It's not visually obvious enough when you have no courage remaining because the indicator is buried in the corner of the HUD.
* The lock-on feature is terrible. It will deactivate when you don't want it to, lock onto multiple enemies instead of deselecting one, and it makes it much harder to path and avoid attacks. However, you need to put up with it as best you can because your Rot attack prompt is incredibly inconsistent if you're not locked on. I'd happily just play unlocked otherwise.
* Combat Camera Assist is on by default and it drove me crazy when fighting large groups of enemies. It's unfortunately buried in accessibility settings along with a lot of other settings that have nothing to do with accessibility, so it took me a while to realize I could turn this off.
* Sometimes you need to un-press and re-press buttons to get the input to register. This even applies to things like controlling the camera with the right stick. I noticed it a lot with heavy attacks too; I'd do one and try to immediately charge up a second one, but nothing would happen.
* While falling, if you hit and release left trigger even for a millisecond, you are unable to draw your bow for the rest of the time you're in the air. This combined with the slower visual feedback that you're drawing your bow when time is slowed down caused me to fall to my death dozens of times. I kept thinking I wasn't actually drawing my bow (which was sometimes the case; you do randomly have to re-press sometimes) and re-pressing left trigger, which prevented me from shooting again.
* The difference in damage between a fully charged arrow and a 99% charged arrow is immense for no apparent reason. I found myself frequently missing out on substantial damage by firing a millisecond too early.
* You need to be standing still for a fraction of a second for some inputs to reliably trigger.
* There is a bit of input lag, which makes parrying more difficult than it should be.
* Sometimes Kena just won't grab climbable walls.
* Irritatingly slow swimming speed.
* Usually after Alt + Tabbing my controller and keyboard would stop working until I clicked something in the pause menu.
* I still have absolutely no idea what the counter means in the bottom right of the Spirits menu.
* I honestly wish the shrine challenges had been left out of the game, as I felt compelled to do them to get all the the cute hats and outfits, but they were a horrible slog that just exposed the aforementioned issues with the combat.
Optimization appeared to be a weakness of this game at first, but performance improved substantially once I switched from DX11 to DX12. For others with non-ancient AMD cards, I would recommend you try DX12.