To be fair to them, I have used them before and so have a few members of my familly. On bangers the prices dont seem very good, but may still be ok if you have a car with some kind of problem that would make hard to sell private.
Cars that are a bit newer seem to command better prices, really its just an easy no hassle way of getting rid of your car, they sent the money into our bank account the next day!
I would use them again...
Just my experience really,
Fabz