I'm just about to implement my first responsive ad unit. Subscribing!

Are you using the default responsive ad code that serves 320x50, 468x60 and 728x90?

I'm running both the new responsive ad units and the old-style approach to responsive ad serving (using JS) on my main site. I'm comparing the exact same set of ad sizes in the exact same page location but with different page topics so the comparison isn't perfect. Other than that everything is the same. I'm not noticing any great differences in performance between the two except perhaps in loading time (which sometimes is noticeable and sometimes is not). The crazy drop I took in clicks earlier this week affected both types but before that (and even during this latest crash), both seem to perform about the same from a CTR perspective. Haven't had a chance to analyze CPC between the two yet but revenue overall (from day to day) has been so crazy that it's impossible to trust the short term numbers and draw any conclusions.

"Are you using the default responsive ad code that serves 320x50, 468x60 and 728x90? "

Yep, the off the shelf Google code. Given the (so far) poor results, however, we're thinking maybe use the regular ads and just swap them with some javascript, which I think Google allow.

Given the (so far) poor results

Could you define poor results please?

In other words, poor results compared to what? Do you have a responsive website and were you serving ads responsively in some other way before this to have something to compare to? If you're using Google's default's, are you replacing a similar sized ad (at least the same desktop size) in a similar page location? The difference between how the ad is made responsive (to me) seems to be the least relevant issue. I'd be more worried about how it fits on my page when viewed in different devices. Using Google's defaults might not work for your layout. I almost always have to use different ad sizes than the Google defaults and too. Both responsive solutions that Google offers work. I find the async version to be a lot easier to implement and more friendly to my visitors. If you don't mind the possibility of the ad slowing down your page load, use the old style ad. If you're like me and user experience is most important, then use the async version and get your content in front of your users as fast as possible and let the ads load when they get around to it. I haven't noticed any great delays in ad serving but other may have. To be honest, I don't care as long as ads aren't ruining my visitors experience and I'm getting a decent click through rate from the ads that are being served.

I reworked one of my sites recently. As a result of this I started using the new Google responsive adverts and use media queries to pass in the appropriate maximum ad size. The actual implementation was straightforward and presented no problems.

BUT....
Just recently the click rate to this one site appears to have suffered. But worse the typical CPC has fallen through the floor.

It is interesting that the revenue optimisation indicator has also fallen to one star.

Almost all of my adverts are targetable (including these new responsive adverts) as the site attracts advertisers because of its location specific content. On the surface it appears advertisers are shying away from these responsive ads.

At this point I am still debating whether to go back to fixed (and according to Google - popular) formats and do the responsiveness with javascript. But currently it appears that the new google responsive ads are costing me money.

I hope Google soon start promoting the responsive adverts, which it appears that at the moment they are not.

Very interested to know how other folk get on.

Mine are keeping pace with my non responsive units. No issues here (and EPCs rising nicely this month)

Thanks for the reply netmeg..... Maybe I'll hang on for a while longer then.

I'd really like to see the responsive ads work well.

I'm still a little concerned that the revenue optimisation indicator is so low although I know it is only a bit of Google fluff.

Same performance here for responsive vs non responsive ads. I spoke to my adsense rep and he told me the available ads are the same for both types. Only for ads with custom sizes the stock is smaller.

I'll just add that all I use are responsive units at this point and am doing better than ever. Smart sizing is a really cool feature for my site and give me a very flexible way to display ads. Still get plenty of standard sized ad formats on desktops and tablets while also having big days on mobile as well. If your site is responsive, it's the way to go IMHO.