I think that is totally awesome that Ford is offering such an extreme car, for an affordable price. It will make a ton of car-dudes happy, and that is always a good thing.
It won't make me even think of selling my M3 for such a beast....The M3 is a different animal. I have driven the latest Mustangs, and the interior refinement (or lack thereof) really puts me off. Although the new chassis is certainly tight, it is no M3.