We, a family of 3 with a 9-year old, enjoyed our stay of 4 nights with Josef, and can recommend the apartment to you, if you're looking for a clean, affordable stay, located in the center of Prague and in walking distance to its old town and all other neighborhoods of relevance to a usual trip there.
While the apartment rather felt like being part of a boutique hotel to us than a private property, it absolutely offered an experience as showcased via the pictures and as described via the list of amenities here on Airbnb. The only critical remark to share from our side, is that we wouldn't call the kitchen a "full kitchen" but rather a "kitchenet" - it is kind of installed in the hallway (though separable via doors) and it doesn't offer a baking oven or the necessary space for busy cooking. However, the pictures here show it accurately, and it's absolutely sufficient, if you don't plan big cook-offs or something like that. Another point to note might be that there's no dining table available, but a breakfast bar (with only 2 chairs though) in bedroom 1.
Anyhow, we would stay here again and even consider doing so the next time that we visit Prague. To us, a clear recommendation, if the points above aren't important to you.