there is also vimgolf[1] for a free and more challenging alternative, in which you solve various text editing problems with least number of keystrokes. it has a nice cli[2] that retrieves problems to the real vim editor, and submits scores. it is interesting to see how other players in the leaderboard solve the same problems differently, and you learn a few useful tricks along the way.

1: http://vimgolf.com/

2: https://github.com/igrigorik/vimgolf