It's been around longer than I can remember, and I started in music in the late 1960s!
It does work, but personally, I think it's a dead end street, as if you learn to play using Klavar, that's all you'll be able to read and play. You'll be missing out on all the music that isn't available in Klavar format.
Our conventional staves and notes have been around ever since Guido d'Arezzo wrote that first red line to mark a definite pitch, and then went on to develop the musical staff - around 1000 years ago. Nothing's replaced it or bettered it, IMHO!