It looks interesting but, like other products in a similar vein (like the Nostromo N52), it seems too gimmicky and outside the regular "comfort zone" of a normal keyboard/mouse combo for people to put the money down to buy it.
Then again, people once said that about mice with more than two/three buttons and keyboards that have "extra" bits and products like Razer mice and some Logitech keyboards are enjoying some popularity now.