Not sure what it's worth, but I'm at 460+ transactions (or 500+ if you include all the cancellations).
I've received noticeably used pairs twice, size 10 in a size 9 box (purchased size 9), one time UPS delivered to some other random location, and one time they sent me two pairs when I only ordered one pair. About 1 in 11 or 12 orders has been cancelled so far, usually when the price goes up soon after my bid was accepted (they stopped keeping track of them in the history section of their site at some point fall 2017, but I still have all the e-mails). They also stopped giving coupons to buyers for cancelled orders even though that's the reason they have stated on their FAQ's for charging sellers fees. I also randomly get switched back and forth between 2-day shipping and Ground (which is over a week from Detroit or NJ). Also, my last purchase came all the way from the UK, so that was about 2 weeks in shipping alone.
I had to file a charge-back once when I placed a bid for one number and they sold to me at twice the bid (their app was having other issues at the time as well). They told me I was banned forever, but they didn't ban me and the next day they said they were making a one-time exception for me.
Worst problem I've had was as a seller when I bought a Supreme piece, left it in their sealed packaging, sold the piece again and they told me it was used even though I had never even opened it and they shipped it to me in a sealed package. They ended up having me ship it back to them and honoring the payout after they looked into it (although they again said "this is a one-time exception").
It's not all problems, obviously I use them quite a bit, just wanted to share the few stories I've had along the way.
