We had the best time staying in Prague at Petra's flat. It was our first time in the city, and we were astounded at the convenience of the location. You would be very hard-pressed to find any apartment in the city with a more walkable location.
Upon arrival Petra was waiting with keys & instructions to the apartment. Our handoff was completely seamless. We were initially a bit concerned about the proximity of our neighbors for noise related concerns, but ended up having no problems at all. The apartment doesn't shut out noise well, but the neighbors were asleep before we were home every night.
Overall, we were completely happy with our stay. We felt so secure, and were just completely thrilled about the location.