We stayed at Jan & Jana's place last week and had a great time. It's a lovely spacious apartment with everything we needed. Lots of nice little extra touches like a range of drinks available, and toiletries provided. The portable wifi dongle was also very useful. Also having things like a washing machine and iron which you wouldn't get in a hotel was very handy. It was very clean and a good location, just a short walk from the Metro. We also felt very safe walking around the local area, even at 2am. There are a number of shops, restaurants and bars locally if you don't want to venture into the city centre all the time, but it's so quick and cheap to travel around Prague (Around £4 for a 24 hour ticket to use buses, trams, and the Metro) that we took advantage and generally travelled into the city.
As we were out and about most of the time, we only used the apartment for sleeping and showering, but it would have been a great place to be had we wanted to spend longer in there. If you're looking for a great alternative to a hotel, then I would certainly recommend this apartment.