This is one of the less popular sites, I have not had enough time to collect reliable review information about sales level.
Featurepics recently changed their pricing structure by 'flattening' new microstock upload prices, and allowing only authors of 'midstock' images to set their own price. Previously it was possible to set the price of all uploads. As was seen with other sites (snapvillage etc.) allowing user selected pricing leads to confusion not only amongst consumers but also with photographers who might not be used to setting a price for their work or how to value it appropriately.
The commission set-up is very good, you take 50% of the selling price, 60% and 70% options available for premium 'midstock' images. A standard image is USD $5 (for our typical 1200x1600), not the best value for the buyer (lower resolution available from $1), but a great commission for the photographer.
The year to November 2016 see a handful of sales for me earning just a few of dollars (and its been that way for several years) Featurepics is a "site I'm keeping my eye on", but things are not moving very quickly. An update of the site a couple of years ago some commitment from the featurepics team to develop their business but not much else seems to be happening