Pro Use Mario licensed graphics to create your own levels to play in
Mario Maker is about the user creating their own levels of Super Mario through the use of design tools and assets that can be found in a wide array of Super Mario games. This means one can mimic or expand upon ideas found in pretty much any Mario game that exists.
Con Levels can be randomly deleted
nintendo has stated that any level that is uploaded online may face deletion if found to be "unpopular" after an amount of time. How much time this is or what specifically "unpopular" means has never been defined by Nintendo, leaving users to see their content deleted at random.