I posted this earlier already, but here it goes again: I was extremely impressed with the speed of the 3GS. It feels a lot snappier than my 1st gen Touch in regular use, and application loading an more importantly framerates were 2-3x higher for sure. I tested this with Zen Bound, the game I knew was chugging with framerate on my Touch on any more complex object level, but on those same levels, 3GS kept near constant 60FPS, which was 2.5-3x better than on my Touch, that kept maybe 20-25FPS at most on those levels.
In regular use, there was never a moment where I felt like I had to wait for the device to respond to an input, no matter what I tried to do. Definitely not the case with my Touch.