I haven't used Leopard very much at all... I had it on my Macbook for a brief period of time.. but switched back to Tiger cause it felt too different.. I also remember some compatibility issues.. but then again, I was using it when it was just released. Am I missing out on anything here? I'm pretty happy with Tiger. I was going to format the HD but was thinking about buying Leopard.. but I could always keep using Tiger and save that money towards the new iphone or something.