About a week and a half ago Google Turns AdWords Yellow & Changes Click Behavior. In short, Google changed the top sponsored results background color from blue to yellow and only counted a click of that ad if it was on the title of the ad itself.
I wanted to wait a bit to see how this may be impacting advertisers. I have some information for you now.
A WebmasterWorld thread has continued discussion on the impact.
One member named lynnemezine said that they are seeing "both a decline in CTR on all ads and fewer clicks on any positioned T1-T3." He is frustrated because he doesn't know if the drop off is due to the yellow background or the change in click behavior required to be taken to the advertiser's page.
Advertiser, "Israel," said that although his clicks are down "quite a bit" his sales remain the same. This member is happy about the click through change, because it drops the number of "accidental" clicks on those ads - which I personally agree with.
SanDiegoChicken said that he has seen a "20% drop in CTR, across 12+ campaigns with over 400,000 impressions this month.
Overall, it appears there are now less clicks in those top ad spots. The big question is why? Is it due to the ad color change or the click behavior change or both? Everyone agrees that CTR is lower, which does impact one's ad ranking in AdWords. But are sales less?
Forum discussion at WebmasterWorld.