I haven't been having the easiest time with my Leopard upgrade.
After my first attempt to upgrade, I got the dreaded "blue screen hang" on startup. This afflicts some number of systems, where after the install, all you get is a blue screen. After a couple of tries, I did a clean install and that worked better. Fortunately, I didn't follow Ben Galbraith's advice and "pull the switch", and I'm so glad a made a complete backup first!
I imported my settings from my backup and the vast majority of things just worked, including applications (/Application and ~/Applications) and most settings. Not my printer, though.
I'm still trying to figure out how to get svnserve up and running again, which is no fun, as I had just figured it out for Tiger. I'm getting a permissions problem accessing the files as user _svn (Leopoard puts an underscore in front of all system or daemon user ids and groups). I don't understand exactly why.
Other fun ... I decided to move to Mail.app from Thunderbird, since Mail.app can import Thunderbird mailboxes. For some reason, it only imported my older mail, so I have to keep Thunderbird around to access all my mail from 2007. 2006 and earlier imported. I don't get it!
Eclipse has become unstable for me. That's no fun, it's been getting memory access violations and crashing hard. So, this is a new chance to try IntelliJ. I'm already like some things, but I've also already hit a couple of bugs and the shear wealth of options and terminology is overwhelming.
I haven't tried out Time Machine yet, I may give it a whirl tonight.
I'm starting to adjust to using Spaces and have closed up my Mac's screen; with multiple desktops, it's just simpler (and better for my posture) to use a single screen. I may have to get a camera for iChat.
I immediately moved the Dock to the right side of the screen, to turn off the awful, stupid, distracting look they introduced.
Leopard includes the svn suite by default (I'm not sure if Tiger did); using MacPorts to install Hugs and erlang was easy, but ghc is a mess because of something that's changed between tiger and leopard. But who has time to study anything new when they're busy trying to finish Tapestry (and learn IntelliJ)?