I used House Simple to sell my house last year and have to say that getting the house on the market was easy, however... don't expect much feedback from viewers, very limited requests for feedback takes place.
The problems properly began when the buyers put in an offer, HouseSimple failed to mention to us two key conditions of offer 1) kitchen appliances to be included and 2) timescale of completion. This led to lengthy delays.
We were then informed that the buyers wanted gas and electricity checks doing (on the 10 year old house), we reluctantly agreed to meet half the cost only to be told by HouseSimple that it was our responsibility to meet all the costs. Our solicitor then advised that if the buyers wanted checks doing it is up to them to do it, anything else is good will on our part.
When we explained this to HouseSimple they then suggested we had cashflow problems and maybe "the buyers should pay for the checks, but for every £100 they spend we knock £500 off the sale price!".
I eventually told them to re-advertise the house unless the buyers put half towards the cost of checks which eventually got the sale through.
The amount of stress caused by this company was ridiculous, seriously don't expect any help with negotiations.