Don't know about that company but I have used a similar company I found online to sell my house. Such companies are prefectly legit and use Licensed Conveyancers to do the work. See here -
http://www.theclc.gov.uk/about.asp
Such organisations are specialists and only do property conveyancing work. They do not employ people with full Law Society credentials (solicitors) and hence don't have the overheads or salary structures. I am willing to bet that if you chose to use your local high street solicitors practice, the person who will actually do the work on your house will be a Licensed Conveyancer anyway - working under the management of a full solicitor.
Whilst I wouldn't (yet) be happy to BUY a property using one, once its sold, its gone.