Yesterday, I got my Mac OS X 10.2 CDs. It's always a feeling of relief when you get something you bid for on Ebay. I was running 9.2 on my iMac so it was just an upgrade install. But it took over 2 hours to do the install! Fortunately, I got it installed on the first try. I'm not sure what it was doing, but it seemed like it must've been compiling source code from the CDs and installing every language and printer driver on earth. It took one hour to install from the first CD and less than 30 minutes on the second. Then I upgraded to 10.2.8 via the web which took over 30 minutes.
The user interface is much nicer on OS X compared to OS 9. OS X feels professional, whereas OS 9 feels like a toy. (The friendly Mac face on bootup is gone) The OS is completely different and is not backwards compatible. So to run legacy apps, it has to start up OS 9. One thing I do miss from OS 9 though is the bootup and shutdown times. Shutdown in OS 9 was almost instantaneous. Though shutdown on OS X is much faster than Linux and a little bit faster than Windows.