I stayed in Martina's apartment for the entire month of October, working remotely on my computer, so I will be reviewing from the perspective of a long-term stay.
First of all, Martina and her mother (your neighbor for your stay) were kind, friendly, responsive, and helpful. When I had issues with internet speed, and I suggested we add a 5Ghz network in her router settings, Martina helped me with the information I needed. When I couldn't find a tool in the kitchen for cooking, Martina had it in her own apartment. And Martina's mother shared some fresh fruits from their garden and jams she made, which was a sweet gesture.
The greatest strengths of this apartment are the location, and the living room. It is located in the city center, about 10 minutes walk to three different grocery stores. I was not woken up at night by noises from the street (and I'm a light sleeper!), although there was some construction noise from the neighbor on some days, always after 8am. The living room is large and beautiful, with many interesting objects and art that Martina has collected, and nice old furniture, along with a good desk for doing work.
Since I use the internet every day for work and video meetings, I need to point out that Martina's wifi is 20mbps down, but the wifi signal can be very week depending where in the apartment you are. When sitting at the work desk I got between 10-20mbps, and would periodically have bad lag, which wasn't great. Unfortunately, the signal is too weak to access it while in the kitchen or toilet.
The kitchen was also important to me since I cook a lot, and while Martina has a good collection of tools, and an oven (which is rare in Prague!), the kitchen is quite small, with very little free counter space, and a very small range. There is no ventilation other than a low window, so if smoke gathers it will gather at the top of the room.
AN IMPORTANT NOTE: Martina does say this clearly in her description, but you should understand that the shared entrance room is between the bedroom/living room, and the kitchen and toilet. This means that if you want to go use the bathroom or grab a glass of water, there's a chance you'll run into Martina or her mother, so you don't have guaranteed privacy (no running to the bathroom in your underwear!). Also, the shower is in the same room as the kitchen.
I loved the bidet for the toilet, which is rare to find. I did NOT love the sinks - the bathroom sinks were tiny, so water splashes everywhere. The kitchen sink is tiny too, and the faucet is so small that it barely reaches the sink itself.
Also, although the apartment is listed as having 3 bedrooms, you should know that one of those is a futon couch/bed, and one is a regular couch that has a pull-out mattress. The main bed is the loft bed, and unfortunately is really two twin-sized mattresses side-by side, and there is a noticeable gap in the middle of the bed that is very uncomfortable to sleep on, so if you are alone you will really only use half the bed, and if there are two of you there will be a natural divide.
I can definitely recommend this location for a shorter stay, due to its location and the quiet at night, and the lovely living room. For longer stays or if you're working/cooking, be aware of the wifi issues and the small kitchen.