I've had a good play around with Arduino's in the past, made a few musical interfaces.

The languages you code in are pretty straight forward and I had great fun but it does take time.

There is an end less sea of info on the net though and plenty of code up for grabs.

I also managed to integrate Max/MSP (if you know that) and use the JavaScript function in that (if you know JS as well)

Never used one in a robot though.