We've only just had our Amazon sales kick into hypwerdrive in the last month.
Initial feedback was very slow and one of the first we received was along the lines "very good service - would use again". Yes, you guessed it, only four stars.
Don't worry too much about the low feedback. Amazon's feedback is nowhere near as regular as eBay. We've sold five or six hundred items now and have feedback of 24 (4.9 average).
One thing to watch out for is Amazon's systems causing you problems. This morning I received an order that was placed on 24th August. Due to payment problems, they only gave us the go-ahead to ship it today. Funnily enough, they have already marked it as a "Late Shipment" and this will show in our seller metrics. They told me on the phone that their people will know what caused this and it will not cause us a problem. It is still quite annoying.
Their systems are far from perfect, but they expect the MarketPlace sellers to be better.
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