I've watched this in English, Japanese, and now read it.
This story still rides on top of almost every single other story I know. It could hit harder because I'm a musician and thus constantly am relating to Kosei and Kaori, but as a musician, the ups and downs they go through, along with Takashi, Emi, Miike, and Nagi are some of the most honest writing of musicians I've read. I was always a little anxious to read it after watching it because, as is obvious, music is an auditory experience. Trying to express the thoughts, emotions, etc. on paper is not an easy thing to do. Yet, Naoshi Arakawa does it in a way that translates beautifully.
The art style is wonderful, allowing for the seriousness in tone and style that comes to the matured art form that is a stage performance, and then shifting to the more lighthearted style that comes in middle school. The laughter, the anger, the joy, every little spike in emotion that we all experience as young teens and pre-teens.
The story, as I previously mentioned, tears me to pieces. While there's the ever present question that people have still been trying to figure out for as long as I can remember about what Kaori is dealing with, to me, that doesn't matter in the end. The story wouldn't change if it was a real or made up thing because what matters is the characters and how they change and grow throughout the story. How they deal with love, loss, and facing their futures.
There's very little I would change to this story. Maybe that is because I'm a musician, because I'm a romantic, because I've walked in their shoes in more cases than the average person. But whatever it may be, this story is still a masterpiece to me after watching, rewatching, and now reading.