Location was amazing! We walked to everything we wanted to see in Prague. The only tricky bit was traveling from the bus station to the apartment and then from the apartment to the airport - but Ilia and his colleague were AMAZING and helped us through that process first by PICKING US UP IN A CAR at the train station (life saver with our broken suitcase - this also helped us avoid getting gouged by a taxi driver taking advantage of tourists) and secondly by calling a cab for us when we were leaving for the airport.
"Design & Love" provided us with a map of Prague's city center along with a detailed description of how to get around and recommendations on what to see and where to eat. Their office is also right next door, which meant we could pop over to ask any questions during normal business hours.
The apartment doesn't offer much privacy (it's a studio) or natural light (two windows, both of which would be easy for others to see in to, so we kept the blinds closed), but we weren't in Prague to stay in the apartment, so we had no issues. It fit our needs perfectly and I would definitely go back.