This games soudtrack is very pretty, a little bit sad, but overall nice to listen to.
Its mostly instrumental pieces but a few tracks have lyrics (though if you've played through the Narcissu games you already know this). The music is generally slower paced with a sad atmosphere, though there are a few slightly more upbeat tracks as well.
As said in the other reviews, it doesn't change anything in game and the content is already free to listen to in the game extras. But this package gives you the MP3 files which you can access outside of game; which I like because in game you can't make it play as a playlist and have to click through each song individually.
I recommend this if you'd like to support the creators / translators of Narcissu or just want some easy listening music for when you're working or doing other stuff.