What are the advantages or disadvantages to MMF instead of regular fondant?
Is it easier to work with or taste better or what?
MMF is less expensive than buying any ready to use fondant. The only fondant that doesn't taste pretty good is the Wilton fondant. Wilton handles great, it just doesn't taste very good (although some people actually like to eat it.)
There are several other good commercial fondants, and many good recipes for fondant in the recipe section.
It is good for beginners to start with a ready to use product, to get the feel of what fondant should be. When you make your own, you will know when to stop adding sugar to prevent if from getting too dry.