It's rare when something like Charlotte comes along, and I feel a little lost for words on how I feel about an entire experience. I know I'm not alone here. What started off as a slice of life Angel Beats style, very briefly became School Days, before moving into Clannad, and finally settled into its own style for the ending episodes. I'd even argue there's a little Haruhi Suzumiya in here too at times. Universally, it's agreed that it was around episode 7 that things started to change, with the seeds planted beforehand. It was from here on that the biggest transition occurred, and we were left wondering what genre this actually fit into, and what angle it was aiming for.
I'll try to avoid spoilers as much as I can, but it's difficult to talk about what makes the Anime so great without going into at least a few spoilers. First off, let's talk about what Your Lie In April [YLIA] is broadly about. Arima Kosei used to play the piano as a child, but his Mother [who was unable to live up to her full potential, due to a terminal illness] placed unnaturally high levels of pressure and expectation on him to compete and do well with the instrument. Killing all the joy Kosei had watching his Mother play the piano as a child and enjoying playing it himself, he eventually forgot about the instrument and stopped playing all together. That was until he met Miyazono Kaori, a high-on-life blonde violinist who wishes for Kosei to play as her accompanist on stage.