In a word, Leopard is amazing and makes the Mac even more fun to use. And probably more productive too, but I guess that comes after you have fun with it. But there is one small issue to do with x11 not working properly. A bit of googling brings up this post:
But the relevant info is here, about 10k words down the page 😉
I reinstall X11 form the original leopard image. All the package X11User.pkg (hidden in /Volumes/Mac OS X Install DVD/System/Installation/Packages), X11Documentation.pkg and X11SDK.pkg from /Volumes/Mac OS X Install DVD/Optional Installs/Xcode Tools/Packages.