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.
Overall the site is professional looking, and gaining a market share, alexa ranking is better than most of the 'trailing sites' so it might be worth investing a little of your time in uploading a few images. I really do hope that this site becomes popular!
2011 saw just a handful of sales earning a couple of dollars. Featurepics is a "site I'm keeping my eye on", but things are not moving very quickly, a recent update of the site shows some commitment from the featurepics team to develop their business.