The apartment was clean, but there was a persistant odor lingering around that we couldn't shake off. The heating was working as expected, and so the rest of the facilities. At night time I would not trust the area too much, but we never had any real problem. The main issue is that the shops around, as well s the streets are really dirty, and in the morning we did find the usual share of vomit around.
Staff was helpful and polite. Please be aware, when booking, that this is NOT a hotel, and the reception is NOT open 24h. So, if you are flying in late, make sure you have ample time to get to the location (almost 2 hrs from Heathrow).