I'm not sure how to rate this game because I think the way it tells a story is really good, however, I don't think it's £15 good.
There's about 3 hours of gameplay, maybe less, and literally 0 replay value to the game. It's very hard to miss notes because you pretty much have to get them all to complete the game.
The story is good, but once again, the game is so short its frustrating. If the game had some sort of expansion pack or something like that, then I think the game MIGHT get it's value out of it.
If this was £3,99 or even a free game, then the score would be a different story. But the fact that the game is so short, and so pricey, I cannot give this game a recommendation.