hows the arduino leonardo?

Has anyone used them much? I actually don't see too many clones on ebay, and there actually not much cheaper that the official one,
is it worth 20$ to play around with?

Supposing that the vinciDuino is like Leonardo, then it is the only board I use right now. I find it scalable, flexible with very nice feature set.
User feedback I get from the vinciDuino is very positive.

I have one, and a couple of 32u4 breakout boards. If you don't need the special features that the 32u4 chip provides; ie. USB device emulation or the ability to have serial debugging and still use the normal serial pins I don't see any reason to get one if you already have other arduinos that meet your needs.

Yeah im thinking maybe ill incluse it in a design for simplicity of usb connection, but maybe not worth the dev board