We have just returned from 2 nights at 4Rooms. Luca couldn't have been more helpful or efficient from our first enquiry to seeing us off. We had the pink quad room with it's little balcony and our friends had the yellow room. Comfortable beds with loads of pillows. Lots of hot water - decent water pressure, not always the case in Italy!! Good breakfast, on the balcony if you want! The best location for seeing Piazza dei Miracoli early in the morning before the crowds arrive.
The only drawback is the traffic noise which may disturb some so if you are a light sleeper bring earplugs. We would definitely stay here again and recommend 4Rooms.