No, unfortunately not me, though it seems everyone else has had a chance to play with one. A really nice overview is on 360Hacker.net where he goes through the controller, console, and everything.
I think what sums up the whole experience for him is this short quote from the article:
You could bring home an Xbox 360 on launch without a game, and still be entertained for hours. Microsoft is a software company–that is what they do best–and it shows.