Mac is the most user friendly unix system ever designed. If you like Unix you will like mac.
If you are a developer I think you will love mac.
Following reasons
1. Real Unix terminal with all default commands, not like windows terminal that craps all over the place once you use
emacs on it. (Single biggest driving force for me)
2. Emacs, ssh, more etc all come in by default.
3. Interface is so much better (This is subjective)
4. Spaces! Multiple desktops.
You can argue you can get all this in linux desktop as well but at the moment Linux world seems to
be infatuated with the tablet movement so all their desktops have become unusable. So mac has
become even more indispensible for developers.

With windows you can do all you can do in mac only it will require you a lot of time and effort
to configure stuff. Nothing works out of the box, after 9000th installation you really dont want
to reinstall that pdf reader.

In the end it all boils down to what sort of scenario you were brought up in.
If you started computers from DOS you will like Mac and Unix like systems but if you
started with "Starting Windows" logo you should not switch to mac, too much of 
a learning curve.
But if you are a software developer (Windows independent, aka web) give mac a try (Until they fix linux).