Pros:
-Not having to worry about adware/spyware or any sorts of viruses, preventing a lot of system maintenance.
-Having the Dashboard and all the available widgets for free download.
-AppleCare plan and the great customer service.
-Reliable OS.
-Another pro I find (personal opinion) is that not many of my friends are not well educated with OSX, so they tend not to just use my computer without being asked becuase they really don't know how to work it well.
-Using Bootcamp to install Windows just incase you need to use a program that's specifically for windows.
Cons:
-Trying to find alternate programs that were "Windows Only" (this being more of a personal con, but so far I have been able to find alternates to most of my programs that I used to use on windows, some are better :mac
.
-Maybe they are a little higher priced than normal PCs?? But I do find that you definately get a great product for the price you pay.
These are just some that I came up with off the top of my head