The ability to create custom fields is one of my favorite features, it helps me track what I need for each order so that there are no surprises when they arrive at our doorsteps! It's also great because if we have any questions as customers about their products or shipping options; all those answers can be found in this tool!! We use FILL GOODS primarily due its tracking capabilities which makes us feel more comfortable with knowing exactly where an item will end up before sending them out (or receiving).
There really isn't anything bad i would say regarding Fill Goods but perhaps some people may not like how simple/easy-to understand certain aspects could become? Like maybe having multiple tabs might make things easier than just using 1 tab?? Overall though everything has been very straightforward thus far - nothing too complicated here.