Me and 4 other girls stayed at Marios apartment for 2 nights.
The location was great, the subway is a 5 min walk. The apartment has 2 double beds, but the 5th person has to sleep on a air mattress on the floor or on a very tiny sofa. Check-in and check-out were uncomplicated. Mario is very quick at responding and we were allowed to check-out a bit later as our flight was departing at afternoon.
We had a wonderful time in London :)