I want to write a review here because this anime is unfortunately too underrated and I am in love with it. So, hi! minor spoiler maybe.
Just to get it out of the way: By the looks of it, namely the art, it's not reeeeally good and some shots look cheap, I wish they had done a better job. And you may overlook this series if you just want something quick paced.
Forget all that, where Piano no Mori shines is in its subtle undertones.
Albeit at first glance it presents itself with a known formula of poor boy-rich boy, it goes on and carries much more than the main characters' contrasting realities and the premise of facing the road to become a great musician. It's a tale of friendship, father-son dynamics, conflict and personal growth. You can even see the show as a homage to the polish pianist Fryderyk Chopin (great choice by the way), done so while playing music beautifully, slowling developing the caracters and their personality in a linear, sensible way. The dilemmas they face come from daily, human nature feelings, making it easy to sympathize with the characters and cheer for them as they progress.
It's kind of predictable who wins at the end, but it's the last-episode twist that makes the victory even more special and really wraps the story up so later you are able to picture how their lives are gonna go from there.
After 24 episodes in total i'm holding Piano no Mori in high regards, and if you are captivated by a calm story an memorable moments (those even coming from supporting characters), give this anime a try. You will enjoy it!