Overall it was a good place for us as we did a family reunion in London with 7 people coming from two different countries and it was great to have 4 bedrooms.
We had a flight delayed for 22 hours and the communication around the check-in process was excellent and it worked smoothly.
I wish the flat was cleaner and a little more equipped. Normally you can expect some shampoo and at least some basics like coffee or tea bags.
Also, I'd like to mention that all bedrooms and bathrooms are upstairs. It was not a problem for us, but some may find it inconvenient.