Amazing Idea with GREAT potential!!!
This is a SPLENDID Idea, and pretty good attempt! I think the layout could be a bit better. Getting to the words you want is rather difficult because it's too easy to play the words you DONT want, which often led to a garbled sounding mess not pleasing to the ears. If you could find a layout that allowed for easier, and faster navigation, then this will be PERFECT!!
Anyway, it's a great job non-the less. This is a fantastic idea! Congrats on making the first ever interactive song! I hope to see more awesome projects from you in the future along these lines!