Big Data is real. It's coming. There's no coincidence that the buzz is entering the feedback loop of our community consciousness. And it can do marvelous, marvelous things.
The author is not saying big data isn't "real" - he's saying the term is overused. I agree completely, it's a technical term referring to datasets so large it's difficult (or impossible) to work with using conventional database tools. But lately it's become just a marketing buzzword used by people/companies that are dealing with data that is anything but "big" by technical terms.
In addition to being overused, I think some use the term to refer to anything that's hard to extract and analyze. The datasets may not be that large or numerous, but after all the slicing, dicing and analyzing, they don't understand what they're looking at. "I don't understand" = "big".