-This will contain Spoilers
(This is a quick review that covers the main topics of the show)

As a former Pianist, I can enjoy this anime in the regard that they keep the music playing very realistic. What I mean is I love how they show the hard work it took for Kai Ichinose and Shuuhei Amamiya to obtain such a level of professionalism in piano playing. I also love the realistic piano hand movements associated with playing the piano, It must have been hard to complete such a task for so many pieces they play.
Storyline: 10/10 Music: 10/10 Art/Animation: 4/10 Characters 9/10

Storyline
The story starts off by introducing us to Kai and Shuuhei as children and their experience with piano playing. Kai is the son of a prostitute mother named Reiko Ichinose who does not come from much while Shuuhei comes from a family of wealth and status. A supporting character Sousuke Ajino becomes Kai's mentor and helps Kai achieve greater things throughout the story. Shuuhei's mentor was his parents who taught him strictly. His dad who was also a famous piano player taught his son in hopes of carrying on the legacy. They both gain greater heights throughout the story.

The storyline is so amusing because it covers the life of 2 kids who love to play the piano but come from two different sides of the class status. One being upper class and one being lower class. Later in the show they both run into problems and become separated due to rivalry and competition between each other. Kai is someone who couldn't read music but could play as a natural through emotions while Shuuhei has been taught strictly how to read music fluently.

The pacing was very well done considering that there are only 12 episodes in the first season. They efficiently paced the lives of the two main characters, their troubles/tribulations, and their character growth. Not many anime have the skill to be able to pace shows like this.

Music
The cool thing about this anime is that it is not just modern and quicker music being played, it's mainly the classical music created by the first well-known Pianists such as Mozart, Chopin, Beethoven, and Bach. Mostly all of the pieces played in the anime are extremely difficult to play which makes the music that much more enjoyable. If anyone enjoys classical music, this anime is definitely worth a watch.

Some of the music played in this anime that was played during the competition portions:
-Beethoven: For Elise, WoO.59
-Chopin: Waltz No.6 in D-flat major, Op.64 No.1 (Petit Chien)
-Chopin: Piano Sonata No.3 in B minor, Op.58 ~ IV. Finale. Presto non tanto
-Bach: Italian Concerto in F major, BWV971 ~ III. Presto
-Mozart: Piano Sonata No.8 in A minor, K310 (300d) ~ I. Allegro maestoso
-Mozart: Piano Sonata No.8 in A minor, K310 (300d) ~ III. Presto [Cadenza (Arranged by Keisuke Shinohara]

Art/Animation

To be frank, I did not enjoy the animation/art style that was shown. The horrible CGI used in some anime was also used in this anime which was the dealbreaker for me. Most of the CGI happened when the characters started playing a piece which made it easy to notice. It would have been a lot better if the anime did not contain CGI. If you can get past that aspect of the anime, it is most definitely worth the watch but that is my one definite critique of the anime.

Characters
As I have mentioned before, The characters had amazing development through the story. Kai went from a kid who didn't know how to read music, to someone who could quite possibly play the best pieces of all time. Shuuhei went from being the kid who was dependent on others and was sort of a whiney one, to being independent and brave. Sousuke went from being sort of a shut-in to being open to others and in acceptance of his past.

Overall this anime is one of the best anime I have ever watched and I would totally recommend it to anyone who is interested in music and piano playing!

Reference: link