This story calls itself an audio drama, and as an audio drama I wouldn't care for it. There is one person doing all of the voices (and it can sound a little silly when they do some of them), it sounds like they're reading from a book, and while there are some sounds thrown in there isn't the type of sound effects you'd expect for an audio drama.
HOWEVER, judged as something like an audio book, I think it's a good story. The premise of receiving letters from the past to warn you about your future is an interesting one, especially considering what can happen to you when you don't follow the instructions the mysterious letters give. Throughout the story I was trying to piece together the mystery and mostly enjoyed it.