My wife's bought a few things off there, I've bought one. We've had two initial no shows, fully refunded, only for them to turn up after a couple of months. I'd happily buy from there again.
My wife has been using it to sell a whole bunch of old clothes. Makes me laugh when she has some stuff listed for a fiver and people message you to ask if you'll take £2.50? Jog on. It all sells eventually though. We post it via In-Post or Yodel. Overall she's probably made 100 quid now.