I recently used eBay's dispute resolution process successfully. After 6 weeks of polite but increasingly forceful emails to the seller I filled in the online form and had my money back within 7 days ($60 worth of 4x5 film holders). He was a high volume seller so perhaps it was easier to garnishee proceeds from his other sales?
Unfortunately I embarrassed myself by clicking on the wrong Paypal payment numbers and initially reported David Goldfarb instead of the bad guy! I had bought something from David via Paypal at about the same time and the items were adjacent in my paypal history.
Lesson learned: I got interrupted while filling in the form and it timed out. Second time around I was annoyed and hastily made a wrong selection. It is also very easy to withdraw a dispute I also quickly discovered!
This has been my only bad experience with eBAY in about 4 years of buying and selling - admittedly in low volumes.