Today, I read an article of Oliver Rist, and I pretty much agree with this guy on Leopard, Apple Mac OS 10.5.
PC Magazine: Leopard is the New Vista, and It's Pissing Me Off
It's ture: Tiger just works. Leopard just not works.
Leopard looks wonderful but it has driven me mad. For example, if you enable Parent Control and Fast User Switching at the same time, your dashboard disappears. That sounds ridiculous but it does happen on Leopard. I rang Apple Support at 133MAC for this issue for several times, what they did was only asking me to back up my preferences files and recreate new ones. That did not help at all. The Apple Support engineers even did not know that Apple already published a KB for this issue until I told them.
Tiger is more nice than Leopard, so far.