This anime is one of the rare ones where almost anyone after watching would be crying or about to cry. Other anime can do this but this one will not leave your head for a while.
Wonderful music adds to the already strong emotions associated with the characters. The story is pretty simple but difficult to forget.
The art is really good. It is colorful and nice to watch. Different piano and violin compositions are worth hearing, even for someone not interested in music.
The important characters are few, so it is quite easy to get attached to them. You can't help but think things would have turned out this way if, she would have done this, he should have said that and so on.
The pacing is good, not too fast or slow. It is definitely worth watching, and quite an emotional ride.