Hey all.
If anyone’s interested in trying them, their interstitial just launched today. The traffic is mostly US, but I believe that in time they will have more worldwide campaigns, as happened with their banner. Their eCPM for interstitials seems to be around USD 4.00 - USD 4.50.
More info:
https://developer.amazon.com/public/apis/earn/mobile-ads/docs/interstitial-ad-sample
Best
Thanks for the update
At the same time their banners eCPM dropped by some 20% 
Or at least for me… my revenue with Amazon plummeted these last 2 days.
Actually I think it’s related to this:
http://forums.makingmoneywithandroid.com/advertising-networks/8908-amazon-revenue-doubled.html
Their campaign probably lasted 2 months and just finished yesterday, so the eCPM is back to normal (the revenue with Amazon was indeed high on these last 2 months).
Are you sure? My eCPM is still $1.5 although the fill rate is way down.
My eCPM is down by some 10-20% and the fill rate also dropped by 10-20%.
It seems that the eCPM today is a bit higher than yesterday’s, I will wait for the day to finish and post back here.
Guys, there is a MAJOR bug on this SDK they released today (5.3.9), so don’t release any app with it, wait for a patch.
It will crash your app if the internet is off on a fresh install of the app (nothing cached).