It's just a ATMega128, with a pin attached to every I/O port, as well as the USB interface built in. From what I can tell, it's running at 16MHz, which is plenty for most needs.
As for there programing language, all they have done, is basically written their own method of programming (very close to basic/vb). Once you "compile" the code, it's converted into C, and then compiled for the microcontroller.
This does give you the option to use Assembly, C, or their language. You can get AVRStudio from ATMEL.com, which will allow you to emulate the controller for your self, which is great for writing code in (but only C or assembly).
The problem with their language, is that since it's new, you can still run into bugs, but you can still use the other two languages if needed.
Other then that, it seems like a pretty good deal, since you don't have to worry about making the PCB yourself, and you have access to every port. Plus, for a external USB programmer for one of those chips, it'll cost you around $70USD!
As long as it's well manufactured, I might end up buying one for my self...