We were staying in Prague with 20 guys (students) and this gym was perfect for us. It is centrally located, very large and when you are with such a large group that is going out to party every night in the weekend this is exactly what you need. Jarda welcomed us very friendly, explained how everything worked and told us that if we needed any additional help, we could whatsapp him any time.
And this in fact was necessary because when we came back from the city in the middle of the night, the key cards appeared to malfunction. Even though it was very late, Jarda was available to help us resolve the problem almost immediately.
The facilities in the gym are good; clean showers and there is even a small balcony for those who smoke. There is no kitchenware, only a microwave, but this was no problem for us.
All in all we had a very nice stay at Jarda's gym, and we would definitely advice anyone who is going to Prague with a large group like ours to stay at Jarda's gym!