I've probably bought/sold over 500 items on eBay over the years. I've never had a problem or been ripped off.
I think they've sort of ruined the site, though. As a seller, it's not attractive because the fees are so high.
As a buyer it's not attractive because it's just turned into a site like any other online store. They realized they could make more money catering to high-volume sellers than they could catering to people selling used stuff. The used stuff/auction style items have almost completely gone away and now it's just page after page of brand-new merchandise with "buy it now" pricing.
I think the only categories this doesn't apply to would be the vehicle/boat section. I bought a truck and a motorcycle off the site last year. Easy, local transactions that I picked up for less than they were probably worth.
Former owner of a 1987 Supra Saltare. Current owner of a Malibu 23LSV.