I have been using the Public Release since it came out. I have a PowerBook G3 (2000), with OS 9.0.4 and 384MB RAM. It runs like a dream. The first public release of QT was a bit sluggish, especially, when movies played in the background. Since I upgraded to PR2 Quicktime is playing like I always wanted it to do so. I am very satisfied.
With earlier version I would play a huge MPG file and sometimes not get the desired frame rate (30fps), with PR2 I usually go higher(50 fps), not sure if it is supposed to be that way.