The apartment is perfectly situated at the edge of old town, it's really easy to get everywhere around the old town square by foot. There are plenty of nice restaurants and bars nearby (many of them did not feel that touristy despite being located super centrally, but maybe thats due to our travel time in early November).
The apartment had everything we needed: a comfy bed for two, additional seating with couch, armchair and at the kitchen counter, a huge wardrobe, well equipped kitchen (though we did not really use it as we went to restaurants mostly; coffee for French press and tea was provided, also a capsule coffee maker is available), and a bathroom with a nice shower.
we thought the apartment might be a bit louder because it opens to a busy (pedestrian) street, but it was totally fine at night (again, might be different in summer).
The communication with Josef was super easy and we received all info we asked for but also much more, as guides and recommendations for eating out and drinks were provided.
Some additional remarks: the entrance is through a mini market, which is a bit odd at first but also practical if you need something quickly (they have plenty of drinks and open late). The apartment is on the top floor without elevator, so prepare for a climb. We stayed here with two people and found it just perfect size wise. If you wanna go somewhere outside of old town, there is a hub for tramways including an underground line around the corner, we got everywhere from there and public transport was super reliable. There is underground parking available very close bya at two malls which is not that cheap (~25€/day) but convenient. The apartment is a professionally managed rental, meaning it's not really feeling like at somebody's home but has rather hotel quality.
Overall, we really enjoyed our stay, the apartment was just perfect for our long weekend in Prague. I would certainly recommend it and book it again.