Incredibly smooth combat, really well designed levels. And tough but fair challenges.
I did find the game a bit too punishing, and having to replay levels all the time got a bit tiring. But I still found it enjoyable.

The only big gripe I have with the game is it's easy difficulty setting. It gives you more health, and enemies easier attack patterns. Which is fine, the problem is that it also basically removes all the difficulty and strategy from the aging mechanic. With you always aging one year every time you die (basically allowing you to die 51 times, and even being able to de-age yourself by five years at the shrines). I wish there was an in between difficulty with the easier patterns, without sacrificing the aging mechanic that made the game special.

Still, the combat, artstyle and general gameplay is so much fun that in the end that doesn't even matter.