If you have seen one negative review and a bunch of positive not sure why you're worried - unless the negative talks aboutsuing the company.

You will find some negative reviews about any service, hotel or restaurant - either because some people just like to complain - or they have unrealistic expectations or don;t understand local conditions.

If they take credit cards you are protected - and typcially apartments do require advance payment - since, unlike hotels, if you book and don't turn up they have essentially no chance to recoup their loss.

Naturally you would want trip insurance in case you have to cancel.

We rented a 3 BR flat on Queen's Gate through London Connections and loved it. It was traditional Enlish decor, upscale, and cozy. A woman met us at Gatwick and drove us into London, and then a (grouchy) man drove us back. (He quibbled at the luggage for six women, although we only had one piece plus a carry on each.)

The only problem we had with the flat was that we sometimes ran out of hot water, but we were three mothers with a daughter each and the girls washed their hair a LOT.