I've been using Ebay for many years now and have come to a love/hate relationship with them.
They're great to help get your items sold. Normally its a no fuss deal listing and selling your items. They also have it so you can set up a "store" on Ebay. This has been awesome for us as we sell products that typically are under a dollar. For $15 a month, we can list our items for only $0.30 and they stay up for 30 days! With hundreds of items this saves considerably over the $0.25-$0.30 to just list an auction.
The downside of Ebay is that their feedback system could use some revamping and they are starting to become a monopoly(buying up Paypal and talks of buying VeriSign).
I do think we need another HEALTHY and STRONG auction site on the internet. Until then, Ebay can fit most of your needs.