It's been a long night, but I finally installed Leopard. The reason it took so long is that I didn't have a retail DVD of the the OS. I had to screw around with a diskimage. From the moment I successfully burned the DVD it took about half an hour to 40 minutes to upgrade Tiger to Leopard.

Here are my experiences:

First time booting into the desktop takes forever. I guess that spotlight is to blame for this, but I'm not sure.

Eventhough I had correctly configured network interfaces, the network assistant thingy popped up, and kept bothering me (even after reboots).
Removing it from the 'login items' stopped it.

My Mail (all account were configured as IMAP) was unable to retrieve new e-mails from all accounts. After some poking around I deleted all accounts and mail settings. After recreating the accounts everything worked fine. This is the nice thing about IMAP. You can remove your account and settings, and you won't lose your mail, because it remains on the server.

Adobe Lightroom seems to work, and so do all of my other image manipulation tools.

PGP v9.6.x crashes. I had to remove it by hand. Too bad that there isn't a documented manual uninstall procedure. Guess I have to wait for an update. Just uninstall the app before upgrading.

Initial impressions:

Faster than Tiger

Very backwards compatible. Vista eat you heart out.

The app improvements on Finder, and the Dock are great. Especially the coverflow view in Finder kicks ass, and runs great on my 'old' MacBook Pro.

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Installed Leopard