The moment I read the synopsis and it says 'jazz' in it.. I'm hooked.
And this movie does not disappoint.

Story-wise, it's nice. Love how it highlights the friendship and how music brings them together.
Acting is solid. Though some parts I feel a bit awkward, especially seeing Sen's swagger - but I guess that's the characteristic of Sentaro. I just thought it's a bit overdone. The rest is good.
Best part of course is the MUSIC! Every time Kaoru plays his piano or duet with Sen. Aside from the music, it's interesting to note the setting of the movie is in 1966 - when Japan is in the midst of economic growth and jazz rise in popularity. Not to mention, the influence of Christianity in post-war Japan.
Overall, if you're still not convinced, I would recommend you to watch this movie purely for the music! ^^