My husband and I stayed here for two weeks- including the hottest weather on record! If you’re traveling in the summer, just be aware that you will be experiencing weather like most Londoners: without air conditioning. There were several fans, however, so it works- along with plenty of cold beverages in the fridge!
The flat is very nice - clean and well- equipped with a comfortable bed and good shower. The neighborhood and location is charming and surprisingly quiet with restaurants, bakeries and grocery stores close by.
We were able to walk to concerts at the RAH and felt felt safe walking even late at night. Numerous underground lines are handy as are busses. As several others have noted, the internet is a bit slow but serviceable.
There are three floors and the stairs are steep and narrow. Not a problem for us, but you may think about bringing some slippers or socks with grip.
All said, we had a lovely stay and would recommend this flat for anyone wanting a nice neighborhood experience and a base that feels like a home. I hope we can return sometime soon!