I just installed it on an iMac 600 MHz running Jaguar 10.2.8 and it looks great. It also feels snappy to me.
As for teh theme manager, I hear ya. Man I've been wishing for that for years now even with Mac OS 9. Yes, the Appearance Manager was there, but it didn't "theme" like it was supposed to. What I find funny is that Apple prevented a lot of people (back in the Kaleidoscope days) to fiddle with the Mac OS theme and now they can't decide on which one to use. And this is worse because WE CAN'T FIX IT PROPERLY!
As you mentioned fjdouse, Steve Jobs needs to get back on track with the Mac. I'm starting to think that many of these changes that have taken place are a way to move Apple away from the Mac and into something else. Remember that originally Jobs was against the Mac, while Woz and others were for it. Jobs tried to push for the Lisa and a continuation of the Apple line (non-Mac that is) but when he noticed that it was a failed venture, he jumped ship and supported that Macintosh all the way. Sometimes I lose respect for him only because of things like this. It's a shame that Woz was the one that always got the shaft even though he had the greatest ideas around.