mumsnet is doing more than just advertising the site - if you click through to the faqs you get this:
"The Mumsnet and iWantGreatCare partnership
Our aim is to create the UK's largest, most popular, user-generated guide to care. We're starting with doctors and hospitals and then plan to widen it to all types of care.
What is iWantGreatCare?
IWGC allows the public to rate and review the care they receive. Founded in 2008, it already includes thousands of reviews submitted by patients and carers about the care they have received from both NHS and private doctors and hospitals.
The standard and style of care delivered by different doctors and hospitals varies and this can make it difficult to decide which doctor and/or hospital to choose for yourself or your family.
Mumsnet's definition is 'By parents, for parents' and so it makes sense for us to team up with iWantGreatCare (IWGC) to ensure Mumsnetters' experiences and opinions can help to provide valuable information for anyone having to select care, whether by a GP or hospital specialist.
How will the partnership work?
IWGC aims to create a user-generated directory of Mumsnetter reviews. As the volume of reviews grows, location specific reviews will be provided to Mumsnet Local pages.
Extending the partnership to iWantGreatCare's other services (nursing homes, dentists, medicines) will be explored as the partnership progresses."
Apparently the site was started in 2008
I don't remember them asking mners about this, considering its a 'partnership' and they're expecting us to provide the reviews and information. Having searched for the doctors in my area the site is inaccurate and lacking in information. Plus they are going to link this to mumsnet local apparently 
Sure rate holidays/shops/products, even baby groups/soft plays etc etc but rating doctors who have no real right to reply due to confidentiality issues is insane. It is open to all kinds of abuse and will just end up providing misleading information to people when they are often at their most vunerable and least able to critically evaluate that information.
We have a system in place to complain about doctors and any other health care professional employed by the NHS. We have an organisation in place to help us access that complaint system and provide guidance (PALS). Its not like 'Iwantgreatcare' is the only option.
Plus clearly its not moderated well if there is a huge amount of out of date or just plain innacurate data on there (I found some on a very basic search of my local area) plus all the missing info.
This is not only a stupid idea but a potentially damaging one. There are a great many people out there with grudges for the stupidest of reasons or who are unable to always judge things rationally. The people running this website and website users have no way of telling who is who rendering the website useless.
I may sound reasonably rational and sensible (or so I hope) and I am - at the moment. I also suffer from amongst other things paranoid delusions. You have no way or determining this, and not a great chance of determining when something I say is rational and when it is not, not over a website any way.