I don't feel that I need it but I thought I'd give it an honest try and follow the instructions. I never realized it but when it comes to curly braces and other keys in that corner "{ [ ] } \". I would take my hand off and use my ring and middle finger. Therefore I was under utilizing my pinky. I also noticed that I tended to use the same shift key for all the letters resulting in weird contortions of my hand.

Doing a quick 1 minute typing test comes up at 90 wpm. However programming, with all the mistakes from jumping around I think brings me down a lot more than this. So I found it surprisingly useful.