Ondrej is really friendly and very responsive with messages. It was easy to arrange check in time etc. I needed to leave my bags after checkout time for few hours and he let us leave them in his office.
The apartment itself was nice and modern. It was quite warm as well which is important on winter. Plenty of space. Kitchen is with bar and stools which are good to enjoy your coffee or food.
The location is about 5-7 mins walk from a couple of tram stops. Lots of restaurants and cafes nearby. Including one just next to it which serves good Czech food. If you have more time in Prague i would suggest exploring the neighbourhood rather than hanging out at Old Town the whole time.