When I do, I’m always gratified by the speed and responsiveness compared with OS X, but I do miss the OS X feature set, especially preemptive multitasking, Spotlight, and Spaces. Our old 233 MHz G3 Series WallStreet PowerBook doesn’t get much use any more, but it runs very nicely in Mac OS 9.2.2, and I’m glad have the good, old Classic Mac OS available as a bootable standby even on our G3 iBook and G4-upgraded Pismo PowerBooks, although I very rarely boot into it. Personally, I still use Classic Mode on my PowerBooks running OS X 10.4 Tiger to support a handful of applications I’ve never found completely satisfactory OS X substitutes for, and I use it daily on my “utility” Pismo PowerBook. Classic Mode is not supported in Mac OS X 10.5 Leopard on any Macs and was never supported on Intel Macs.
Mac’s Classic OS continues to fade in compatibility and relevance, with support in crucial areas – especially Web browsers and email software – becoming more and more tenuous.