Looks interesting, but I think I'd go nuts with buttons jumping around (in size) like that. Excellent concept, but I just want my fingers to memorize the position of each button so I don't have to think about what I'm pressing next.
IMO, someone just needs to make a keyboard that makes better use of screen real estate. Why the hell do I have a smiley-face button when the space could be better used for a wider space bar, etc.?