I've been selling on eBay for several years now - we do about $200k a year on eBay and I can't stand them.
I gave up trying to maintain "Top Rated Seller" status, because you are allowed only two 1 or 2 star ratings in any category per *year*, out of a couple thousand transactions. And leaving you 1 or 2 stars is totally anonymous and based solely on the opinion of the buyer. So if you say shipping will be $8 and they think it should have been $6, they can leave you 1 star for unreasonable shipping fees, even if the actual cost was $20 and you took a $12 loss on sending it.
eBay buyers are by *far* the most picky, least patient, cheapest, least understanding and most demanding customers we find anywhere. And we sell premium products that are made in the USA. Amazon is a much better class of customer. eBay is full of cheapskates who want something for nothing and will whine to high heaven if they don't get it.
And eBay management is no better. They place such ridiculous demands on their sellers that I don't know a single one who likes eBay. It is never good business to have half of your customer base despise you.
Not to mention PayPal - essentially an unregulated bank who has their way with users and there is virtually no recourse.