It works….

It’s not a natural feel. you have to keep your fingers up off the paper. The keys are an odd size. Not a full keyboard, so numbers and such are in weird places.

I got the app as a free app of the day thing, but it wasn’t actually free. Still told me I had to pay $3 to unlock unlimited typing.
It worked, but I’ll stick with the onscreen keyboard (a lot more user friendly) or just use voice dictation.

Scott Rogers about Paper Keyboard - Fast typing and playing with an alternative printed projector keypad