I have been selling on eBay since 2005. I have been down scaling my sales activity, but I still sell enough to maintain a Bronze level power seller status. Because of ebay's service fees there is other sites that I prefer over ebay, but unfortunately you are not going to have the same volume of sales with those sites (even though I have a couple of drop ship products which sell well on Amazon.com).
I never made a living exclusively on eBay, but I do make a bit of a side income. I recommend you start with a few items (maybe used items you are looking to make a little extra cash from), build up your feedback, and see how it goes from there.