I am also really impressed - coming from Vancouver, Canada, rain is something you expect, and you need to be comfortable driving in it.
A couple of weeks ago, I took a friend out for a spin. It was raining (of course), and on a quiet highway, I laid into the throttle to show off the growl of the V8. I felt the rear end get a little bit loose, but it was quickly reined in before the TC light even came on. Driving through Utah the other week, I found myself in the midst of a torrential rainstorm/thunderstorm, and the car barely moved out of it's lane, even when passing a semi.
Thumbs up to GM for making an incredibly stable car.