Visitors spend approx 35% more time with pages that use Google AMP

"Chartbeat says visitors to web pages that load with Google AMP are spending 35 percent more time with that content on average than with standard mobile web pages.
On average, visitors spend 48.2 seconds with pages found through Google search that load with AMP, compared to 35.6 seconds on average with standard mobile pages found through search.
That means pages that load with accelerated mobile pages software (that’s what AMP stands for) are more valuable to advertisers, because visitors that spend more time with content spend more time scrolling through ads."

Source:  Recode, 5th June 2017