I wrote this module and have been testing it for the last couple of months. I have/do use paypal google checkout bidpay etc. on my osc site. Amazon Payments is by far the absolute worst:

-No customer service at all. They provide an email form and never answer emails. Customers call Amazons "Indian" Customer service department who have not even heard of Amazon Payments.

-No Fraud protection. Impossible to verify if the customer's shipping/billing address is the same as owner of the Amazon account, All you get back from Amazon is a name.

-Delay in declining orders. Orders are approved at checkout but then declined later.

In conclusion from the guy who wrote the module Avoid Amazon Payments!

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