Google was recently forced to launch a clearer design to distinguish ads from search results to follow updated FTC guidelines put in place on June 25, 2013. The top Ads are no longer as deceptive. Ads were formerly on a light yellow background with a tiny “sponsored results” line of text.
Advertisers and Google of course are definitely concerned about lower click-thru ratios. So far our adwords campaigns have not experienced any significant drops in performance.