It's basically a flying ARM development board, with a 2.4GHz wireless controller. This seemed like too much fun to pass up, so I ordered the kit, which should ship on 5/3/2013. There is a basic kit for $149, but I ordered the $173 kit, which contains some extra sensors - a magnetometer and altimeter.
It comes as a kit, so it must be assembled before even basic flying can be performed. Once that's working, there's a few things I'd like to develop and play around with - for example, there is currently no software support for the altimeter. I'd also like to play with some algorithms for implementing a hover mode, and (re)learn some control theory. Plus I think my kids will be fascinated :) So, stay tuned, as I hope to update this blog as I learn more about the hardware/firmware/software... and hack on the Crazyflie!