HIGHLY RECOMMENDED!
Josef is very friendly and thoughtful. Once you got the confirmation, he will send you a "super-complete" guide about Prague.
He is very helpful in any ways even before we arrive, gave us some suggestions on our enquiries and so on.
The house itself is very clean, spacious and fully equipped. The most important is, a lot of major historical sites are just walking distance.
There are also some restaurant/cafe close to the apartment, as well as mall and convenient store. Basically the location is just really good, we can almost get whatever we need or go to places we wanted to go just by walking.
Overall it was a good communication and we had a great time at Josef's house.