LOL. I think Gartner is jumping the gun.
The Harvard Business Review put devoted much of last October's issue to Big Data.
Nate Silver just accurately predicted all 50 states in the last presidential election.
Facebook just launched a massive new search tool.
And everyday the sheer quantity of data we deal with grows at an accelerating pace.
My team had been using Hadoop, BigQuery, and Python for Big Data problems for quite some time, and we're by no means disillusioned. And we do have a LOT of data. Here's a public dashboard we assembled http://now.youversion.com/
If anything we're excited and encouraged, and not at all disillusioned.
Will a bunch of people wake up one day to discover that they couldn't just buy a piece of "Big Data" software off the shelf and extract business insights from it without any effort? Probably.
Will they eventually realize you need to invest in hiring competent data analysts and fine tune the algorithms needed to extract such insights. Undoubtedly.
However, will "Big Data" fall into the trough of disillusionment in the next few months, or even anytime this year? I highly doubt it.