The place was amazing and very spacious. It was a great deal and a great location. When I arrived at check-in, the house managers were still cleaning (an hour past the check-in time), but it was not a big deal. The amenities were great and the place was great (a bit confusing to get to). Internet worked great, lots of bedrooms, we had 9 fit comfortably.
We also stayed at 1 Norfolk Square Mews, but definitely recommend the other property (12 Norfolk) if you were debating between the two. The Internet was spotty and this one was smaller.
Finally, the house managers hung out outside of the house all day for two of the days we were there. Not a huge issue, but it made some of our guests uncomfortable because they didn't know who they were.
Overall though, I definitely recommend!