Any experience with Amazon Ads?

How is your fill rate? What is your eCPM?

Yes I have also recently heard about them. And since then I am getting quite satisfactory result I would say.

What is your fill rate by country? Do you have experience with other Ad Networks? Thanks!

Fill rate is various (from 12% to 45-50%), eCPM are good at 2-3$ for interstitials and 0.6-1.0$ banners

what are their ads ? amazon products?

I would also like to know if they promote amazon products.

Amazing ecpms, but poor fill rates. You should use this network always with backfill or mediation.
Also, they have a bunch of cost per impression ads.