The location is top notch, and you get an AMAZING view of Prague Castle from the terrace. The main bedroom is quite large and well appointed. The second bedroom is very small - the king size bed takes up most of the space. It was so small in fact that I had to keep my suitcase in the hallway as there wasn't enough room for it in the the second room. The kitchen and bathroom are very small, but functional. Think of the apartment as a one bedroom where the large common area is converted to a bedroom. The beds are comfortable although there is quite a lot of noise if you leave the windows open. The wifi worked very well most of the time. There is a small washer but no dryer, so be prepare to air dry your clothing if you wash. There is a drying rack to do so, which worked well enough.
For negatives, the bathroom often smelled pretty bad, as if the sewage smell was entering the apartment. I believe it was coming from the shower, but couldn't be sure. We ended up leaving the bathroom door closed most of the time, which limited the smell to that room well enough. There was only one set of keys for our trip, which limited us a bit since there were two of us and needed to be together to come and even leave because of how the locks work. We also couldn't figure out how to make the A/C work, at least not effectively. It was cool enough that we didn't spend much time with it.