1.
You can write more letters in less time using shorter pen strokes.

2.
Regardless of what character you write, the probability that the next one will be a vowel or space is 50 percent.
For this reason the vowels and space are placed in the blue window that appears as soon as you write any character. Rather than having to reposition your pen, you simply continue writing.

3.
Because the keyboard has two levels (yellow keys and the blue window) there’s more room for bigger keys: fewer errors, fewer corrections, and better usability.
And it’s also easier to reposition your pen, saving you even more time.