I didn't meet Dominika and Jan, but their apartment is fantastic. The room is enormous! It is literally 2 minutes to the Staroměstská train station, making access to pretty much anywhere super easy. Access to and from the airport is also easy, requiring only a quick bus and train ride. The famous Charles Bridge is only 500 metres away and the rest of Prague's Old Town is within easy walking distance. They have a washing machine in their large bathroom, making laundry a welcome option.
The only thing to note is there are no real curtains in the room, so unless you're OK with sleeping in bright light, you may wake up with the sunrise.
I would definitely stay at Dominika's apartment again if I was to return to Prague.