I did a little more research on it: Ducati has been using a similar systems for the last half century. Mercedes and a few others used a similar system on a few race cars years ago. The synopsis is that the system works well. However it is more complex (ie more expensive and requiring more maintenance) than valve springs. The cam system is also very noisey. And because valve spring technology has advanced so much in the last decade, the cam system is solving problems that no longer exist (valve float, broken springs, etc).
I still want one!