I think it's fantastic. I love love love it. Never sold stuff on there tho, so can only comment as a buyer.
Recently, I've bought 4 Freya bikinis for a total of 45 quid (including postage). If I were to buy them new, they'd be between 50 and 60 each.
Got trainers and shoes that must've only been worn once cos they are in great condition.
Had fancy dress costumes too.
Husband also loves it and buys a lot on there.