I lived in Prague for several years and got picky about the location when it came down to choose a spot, but I honestly couldn't be more pleased - the apartment is at max 2min walking distance to everything we needed, extremely central but still quite quiet at night. Location is hard to beat.
We were 7 people for most of the week (6 girls), and we managed the 1 toilet/1bathroom situation ok enough - 3 mirrors in the house helped too. The beds are big, enough for 2 people (we all shared); the pillows are indeed really big, though most of the group wasn't too bothered. Our advise: bring a sleeping mask if you're bothered by morning light, and pack lightly as there's no elevator.
The flat is beautiful and exactly like the photos, was perfectly clean, fully equipped and ready to move in. We checked in with Jiri who was always nice and readily available. There was one small misunderstanding regarding previously arranged transportation that was handled extremely graciously, and everything went smoothly. We truly enjoyed our time in Prague, and definitely recommend staying at Michael's.