Tiger OK So Far
So far I've upgraded three of my four Macs to Tiger. No major problems. They include a 500Mhz G4 Cube, an 800Mhz Powerbook G4 and my 2x2Ghz G5. I started with the slowest computer and have just finished the fastest.
In general, I am very happy that there is little in the way of gratuitous cosmetic changes. When I sit down and look at the screen, I would not even really realize anything was different. The only things I can see are the little apple menu icon in the upper left, which is bluer, or something; and the spotlight icon in the upper right (which of course isn't there at all in panther). I've already found some documents I had completely forgotten about.
Spotlight is pretty great. I've been jealous of my friends who have installed google desktop search on their Windows machines, but that's all over now. It takes a while to do the initial index, over an hour beyond the install of Tiger.
Dashboard is the other feature that is nice. It's a blatant, heinous rip-off of Konfabulator, but it's executed a little better. I never really got into Konfabulator, but I can see myself using Dashboard quite often.
My one complaint is that the integrate Tiger Sync (which replaces iSync) is a little sketchy. I've already had several odd error messages like: "an inconsistency has been detected. We recommend you re-sync from a Mac with good contact data." Yikes. I haven't lost any data, though, so it's not horrible. The Sync is quite slow, but I'm hoping it's because everybody is upgrading this weekend and trying it for the first time.