My macbook pro is running Tiger (still!), and I don't see any reason to update to Leopard, yet. I think I will probably upgrade it once Apple removes its support.

Tiger is quite stable, the GUI doesn't seems outdated yet, and most of the applications still run on it. But the Terminal app is quite hard to use, you cannot use Home/end keys i.e., you don't have tabbed shells, and it seems that there is no way to enjoy the beautiful tabbed Terminal that you have in Leopard.

But this is no reason either to move to Leopard, as I had to help a friend configure the keys for linux-like behaviour in its 10.5 powered macbook pro.

Googleing a little bit, I found "Terminator", a terminal application based in java, which gives you linux-like term functionalities, tabbed terminals, and all the stuff. And it's cross platform.