Yeah, the example is pretty bad. This layout also seems to be hard so squash vertically without increasing the error rate a lot compared to a normal one. The error rate on smaller sizes is something a lot of novel touchscreen keyboards should probably have focused on instead.

I used minumm keyboard a long time ago and it was actually good, 1-2 cm of keyboard height, sadly I think it's been discontinued long ago, but you can see a couple of screenshots here

http://minuum.com/