Imagination

Coming from a web development background, JSON arrays were also the firs thing I tried with data merge and like Plasma above I was rather disappointed to find that nesting of any level and more complex objects with nested properties didn't work. CSV was fine, and my jsons in this case were easily flattened to something it could parse, but I feel like the merge could be a lot more powerful if it could actually use the full power of JSON as opposed to treating it like another CSV row. Not a fan of the number of clicks required and multiple menus I need floating around for it, but it's perfectly useable and once you figure out the particular way Publisher wants you to use it I've found it works well enough for me.