Celeste is one of the best games I have ever played. It took me more than a year to start playing because I feared it would be too difficult.
It is difficult, but is also amazingly well designed, the fluidity is incredible, you improve without even realizing sometimes.
Setting your own goals and understanding your limitations is important, though. Assist Mode is there to help you and teach you if you need to.

The story for me is a gem. It gave me access to feelings that I didn't understand before, probably the first time I felt something like that through gaming.

A perfect 10/10.