Heard about this site on Radio4 today. It's run by a GP, and bizarrely anyone can add the name of their doctor and post a review of his/her performance. Presumably if your review is unfavourable the GP concerned is informed so he/she can reply.
I entered GP at Falmouth Road and two of the GP's there are listed but no reviews.
I imagine if you did post a negative review you'd be advised to do it anonymously as you'd probably be asked to take your 'ailments' elsewhere.
On the other hand you could post a positive report which would likely be appreciated.