We spend a week in Johnny's place during our holiday trip to London. Even if the apartment is not big, it was completely ok for us (a couple in mid 30'). It's very central - in the heart of Covent Garden - so we were able to walk to many places and even come back and rest in the apartment during the day (we were in London during the heatwave). There was enough space in the closet to unpack our suitcase. We liked the street view and the fact that it's just few steps from a hip cafe. One can also find some interesting books :) A huge plus for us was that there was only one faucet in the bathroom sink!
On the downsides - which weren't a huge problem for us, but it might be good to mention them for others - the bathroom is tiny, and as a quite tall person I struggled a bit, but my girlfriend, who is around 160 cm tall, didn't experience this problem. The WI-FI connection was decent, but it's not a place where you can work remotely from. The staircase is narrow and steep, it could be tricky to climb with a big suitcase and also it's definitely not a place for someone with a disability or for an elderly person.
We haven't seen any famous person, but it's worth mentioning that it's just 9 minutes from British Museum and 2 minutes from very nice pub ;)
It's definitely a place we recommend and plan to come back to!