I'm currently trying to build an RGB Arduinome[1] using an arduino board, and it's my first interaction with µ-controllers. I am loving it. As simple as it is, seeing an LED blink a pattern you just programmed into it is very rewarding. Reminds me of the first time I drew a few circles with BASIC when I was nine.
[1] http://en.wikipedia.org/wiki/Arduinome