We recently used House Simple to sell our propertly and received great service. Being an internet company you do have to do a lot of the work yourself, showing people around, putting the sign up etc, but this is how you save paying the extortionate high street fees. Another thing to note is that you have to set the price. We were aware of similar properties in the area, so went off that but they do offer a \'valuation guide\' too.
We chose the middle option, part up front, part on completion as we were unsure if the propertly would sell. As it happen sit sold within three weeks! The agent we dealt with, Michelle was a great help, dealing with the purchasers and the solicitors, and helping to keep me sane. We only had one other viewing before the offer and we got feedback on this straight away.
Using an internet company, and getting a much cheaper deal than with a high street firm, you have to expect some differences, but having dealt with both for the sale and subsequent purchase, I do not feel there was a service level difference in the two.
I would definately recommend House Simple to anyone. In fact a couple of our neighbours and friends have recently contacted them to use them too.