I've used it and it's great! They even let me know that one of the phones I'd sent was not the one I thought it was but an upgraded version therefore worth more so I got more money.
my son used these he sent 5 phones. Only concern about it was the sent3 separate cheques at different times. would have made more sense to send them all together when they had ALL been tested. So much for saving the environment.
If u look on moneysavingexpert.com and click on the bit about ways to expand ur income theres a list of different companies who do this, u can type ur phone in and they tell u how much they will give u, prices vary, some pay half in vouchers.