As smart phones go all galaxy s phone are great and you can get most apps that you need for free on Android they might not be as visually appealing as on iOS but they get the job done and usually can do a lot more. I love the galaxy s screen but some people don't like it I would advice checking it out yourself first.
If you like to play around with the device jailbreaking etc you might have problems with a mac as far as I know their is no official mac software from samsung but like =X= said their is no real need for a pc with an android device. If you do get the device and would like to mess around with it you might try this Heimdall opensource software that can be used for flashing on Mac
http://forum.xda-developers.com/showthread.php?t=755265