I got to level 4, then I stopped. The game is fun at first, but after a while the slow pace wore me down.
I think the optimal play-style probably is only 2 hands. Specifically, I felt myself just immediately switching to normal typing positions. That wouldn't make much difference, but with the controls gradually overlapping between commands and interfering with each other, I think all the hands being one person would probably be more strategic. Also 3 hands on a laptop keyboard would be quite a squeeze.
The retro feel is nice though.