The installation went really easily. Took 45 minutes on my MBPro, then a longish restart. I had a couple of auto-loading apps, so first request from the system was to install Rosetta, needed for older PowerPC programs.
First good news: Eudora works fine. So does Tweetie for Mac, and AppleWorks' word-processing module. Haven't tested the others because I don't use them. A couple of utilities have lost their registration preferences so I need to re-enter the serial numbers.
Second good news: The space-saving feature is real. I had 98 gigs on disk before, now I have 88 gigs. That's what I call efficiency!
Exposé looks different now. Windows in the Dock are exposed as well as the other open ones. If I don't choose a docked window, it goes back into the dock when I click another one. Dashboard does not appear to have changed at all.
Safari didn't change because I had already installed version 4.0.3.
Software Update offered only Backup 3.1.2 as a needed update. Backup is the worst program for that purpose I have ever seen; I thought Apple dumped it when releasing TimeMachine. I suppose they keep it around for MobileMe. I have yet to meet anyone who is happy with it.
iTunes gets updated to 8.2.1. If you are a Palm Pre owner and wanted to use iTunes to sync your music with it, Apple released this update to version 8.2 for the sole purpose of preventing you from doing that. With Snow Leopard you get it, want it or not. I guess I should see if it can be downgraded. That's the only thing wrong with 8.2.1.
Quicken 2006 opens and I can change data. This was originally not supposed to work under 10.5, but it seems only the online features stopped working then. I never use those features so I never noticed. If you use them, you should probably get Quicken 2007 or later, or a competing program.
The battery seems to be lasting longer, but it's subtle.
I will post more reports when I have more information. Meanwhile, I recommend visiting Macintouch at least to keep up with reader reports on the new OS. These are just my own observations.