The apartment of Marketa and David is great, perfect location - walkable distance from the center (30 min walk), beautiful parks around, very nice neighborhood with restaurants and bars, close to both metro and tram stops. It has all the necessary facilities. Marketa is EXTREMELY helpful and responsive.
The apartment is perfect if you stay in Prague for touristic purposes, very quiet as well. The only negative side is that it is on the ground floor and therefore a bit dark, but if you are not staying there all day long, this is not an issue at all.
I would highly recommend this place!