it looks cooler, might be more secure, and has a newer api for programmers to take advantage of. Honestly, the purpose of any OS is just to allow apps programmers an easier to use, common environment in which they can write something that makes the end user productive. I probably won't upgrade my windows desktops to Vista until sometime in 2009 unless there's a killer app out that I absolutely must have. Same thing with my MacBookPro, I probably won't upgrade to Leopard (10.5) until something comes along and requires me to use it.