I have spent almost 2 months in Alex's place. The communication is excellent, you can expect a reply within minutes and he is very very nice. I met him in person and his family, they are all very kind, willing to help and accomodate you as much as possible.
The position is excellent as well, within 3 minutes walking you are at Earl's Court station which is zone 1/2 meaning if you come from Heathrow airport and get off here (in the non busy hours) you will pay just £1.70 for the direct metro. Also, you Earl's Court has both the Picadilly and the District lines, which bring you almost everywhere in London and at least one of the two is always working (while you cannot say the same for the other lines e.g. Overground or Circle). Also, the bus stops are 2 minutes walking as well, and you can reach Marylebone in 30 minutes. Or, you can walk to Notting Hill/Portobello Market. And the lovely Hyde Park is just walking distance as well! Or the museums in Cromwell Road just 15 minutes walking or Harrods about 25 minutes walking.
That is not all: there are three huge supermarkets close by (Tesco, Sainsbury, Waitrose) so you have plenty of choices, although Ocado could be also used for online grouceries which are delivered easily.
You can expect to feel safe in the building, as there is always a porter at the entrance of the building and video cameras. Also, Cromwell Road feels very safe also for coming back home during late night!
The apartment is really well equipped as well: the kitchen is like your own at home full of everything you might need, including a small oven and the washing machine. I really liked the sofa and the space in this studio, much bigger than what you can find in London. Also, there is one lovely balcony where you can get fresh air.
Two things to be careful about: you should not suffer from traffic noise, the flat is not noise-free as Cromwell Road is super busy and the hospital is just on the opposite road of the building; also, in the building everywhere there is just moquette so if you are allergic might not be the most recommended option.
Overall, I would super recommend, for short but also long stay! The studio has everything you need, including lovely owners!