Way cool! The handwriting feature is very well done, and seems like a decent barrier to entry for copycats.

One critique - when I was trying to write letters that required multiple strokes, such as 'i' or 't', oftentimes the screen would scroll away from me as I was trying to do the second stroke, and I would make a mess. Maybe it should disable writing while the text is scrolling? Maybe a sine-interp on the movement to make it a little more predictable?

Once I figured out to pause as I wrote to let it finish scrolling, I was confused that sometimes my last letter was still visible, but other times I had to scroll backwards to dot my 'i' or cross my 't'. The undo and scroll commands are very good, but ideally I wouldn't have to use them them unless I made a mistake.