Though we never met Jan, our communication via internet was very good, he was quick and responsive.
Apartment is located somehow at the suburb of the city. But transportation in Prague is very good (similar to Paris) and that helped a lot. We took a 3-day full subscription for transportation (~13 eur) and were able to took any metro/tram/bus at any time.
It would have been nice if the apartment would have been ventilated before our arrival. Also, the bed linen felt like it was changed a long time before, there was only one extra blanket (we got there in the middle of the night and we were a bit cold) and there was dust in the wardrobe (we had to clean it to put our things).
There is an iron & table, very handy for those who don't iron clothes before holiday :-)
The bathroom is split in two rooms: a tiny one just for toilet and another one with sink & shower. Both are on opposite sides of the main hall. I assume there are many apartments like this in Prague. Before I saw this "bathroom structure" in Paris, but now I see there are other places, too.
Conditions were not the best, but we didn't pay much either. We spent only the nights in the apartment.
Btw, there is a city fee of 2 eur (50 czk) per person/ per day that needs to be paid.