The apartment was lovely, clean and spacious, with everything you need for up to 10 adults. Some of us were sharing beds, which was fine as the doubles are quite large and we were given separate bedding. Note that if you are going in the summer, it can get quite hot, and there was only one fan. As it is a penthouse, a lot of light comes in through the skylights, which is nice during the day, but may wake you up early if you're a light sleeper.
There are two bathrooms, one upstairs and one downstairs, each with a shower. The downstairs one has two sinks. We were all given towels. When we arrived there was toilet paper and hand-wash, but we needed to buy shower gel and shampoo, and powder for the washing machine.
We were a group of nine and could cook for all of us using the facilities (a cooker with two hob rings, a microwave, a fridge/freezer, and a large dining table) but it did take time so we mostly ate out. There were enough glasses, mugs, cutlery etc for all of us. We found that there wasn't a tin opener or corkscrew, so check you have these before buying cans and bottles.
The location is very good; there are restaurants and shops nearby, and the Old Town is in easy walking distance. Part of the metro line was closed while we were there, but this wasn't an issue for us. If you want to stay in your comfort zone, Tesco and KFC are nearby, but there are also more local shops and restaurants, including a couple of vegetarian ones (although in general, restaurants had fewer veggie options than in England). We liked the Mamy Korean restaurant down the road. Eating out wasn't too expensive, about 180czk for a main and 30czk for a drink in good value places. If you go out to nearby bars, shots were about 60czk each, about half what they are in the busier bars near Charles Bridge.
The 'Visit in Prague' hosts are very friendly and accommodating; we had some questions about check-in times and the deposit, which were answered quickly and flexibly. You can also phone the hosts or visit the office during your stay if you need anything. If you're unsure about booking here, just message the host with your concerns and I'm sure they'll be dealt with.
Overall this apartment was excellent value, especially if you are a large group, and I'd be surprised if there's anything comparable in terms of location, size, and price. Prague is a great city with parks, monuments, museums, and clubs & bars all within easy reach, whether by walking, metro, or tram. Thanks again to the Visit in Prague hosts for offering such a nice apartment for our stay. Děkuji!