Its basically just an advertising site, there is another that does the same, they are no different to any other sites as far as I know, although they handle the initial calls and some arrangements the horses will be in their owners yards and it is just a private sale.
There is a similar site calmequestrian, most of the horses have been listed for ages, one has been on for 2 years and not yet sold so I am not sure that they are really the way to go as probably not getting many views.
They are all advertised as private sales, not the case if they are all in one yard as they are operating sales livery or dealing, there is no mention on the website of sending a horse to them to sell just how to place an ad and the services they offer regarding assistance when buying etc.
to be honest the titles 'safe horses' 'honest whatever' 'perfect whatever' puts me right off, maybe unfair but to me its like all those dodgy tinpot dictator regimes who always seem to have words like ' The Peoples' and 'Democratic' and 'Republic' in their titles, which is a sure sign that they are neither democratic nor run by the people and probably a very rich dynasty creaming off the money.
I would also be wary of any scenario (not saying this is the case here) where a dealer is selling horses but they are all 'on behalf' of client thus denying you the increased rights you would have of redress if they sold it as a trader on their own account, instead they are all private sales where is is basically sold as seen...