Only thing that keeps coming up when I search is that it will be "bigger than Black Friday." Personally, I think one of the main reasons that Black Friday is so big is that people know what deals will likely be on and put off big purchases for that day. I'd love to get some deals on Prime Day, but I'm not likely to spend the whole day online trying to figure out what deals are available (and likely will only be open for a certain number of purchases or a certain time frame).