Dani is a great host: our room was ready a few hours before check-in time and he was kind enough to let us in as soon as we arrived.
The flat is small but nice and clean, the bed is comfortable. As others wrote, the street in front of the apartment is really noisy, so with open windows it is quite annoying. However, the windows insulate a lot, so we didn't have any problems with sleeping (we stayed in November).
The transportation is outsanding in the area: in 3 min. walk there is a tube-station, a bus stop (with direct line A1 and A2 National Express coaches to-from Luton Airport), and in 15 min. walk there are two train/overground stations link to various airports and neighbouring cities.
Our only problem was the tap-water: I don't know if it just the building's system, or it is the problem of the whole city, but the water had a really unpleasant taste and even odour. So we had to buy bottled water for drinking.
All together I would definitely recommend this flat and would stay there again.