First of all, we should mention that we stayed for one whole month in Beyazıt's studio and that helped us notice the pros and cons about this place.
The pros are that the location is really good since you have the metro, ferry, and bus station just a few blocks away. Also you are surrounded by some minimarkets, stores, and restaurants.
Additionally, our host was kind enough to help us with the luggage and providing shampoo, oil, and some kitchen utensils, even though were very old.
Now the cons: We started to see some problems since we got to this place; problems that increased to the pass of the days. For example, on our first day we noticed that the towels had some green and red spots on them, this means they were not washed before our arrival!!! (we had to buy new towels!) Moreover, the comforter, pillowcases, and the bedsheet that covered the mattress were not washed either (he told us he washed the towels and that the bedding set was new, which clearly was not!). The bathroom door was hard to close, since most of the time it would open by itself. The countertop of the kitchen was still dirty and with oil. We had to buy cleaning products to clean everything. Also, the furniture is really old. The fridge stopped working properly on our 3rd week, to the point of spoiling a lot of our groceries. We had to throw away meat, cheese, yogurt and vegetables after 1 weekend off, when we left the apartment for a short holiday (fridge is also very noisy). The sofa has some cigarette burns, and lets not forget about the constant smell in the bathroom. I'm not sure if the sewage of the building is working properly, but the bathroom kept smelling all the time. There is a constant repair inside other apartments of this building, so you would constantly hear drilling noises in the morning and afternoon, even on the weekends. We asked our host when he was going to stop and he blamed the building next door, when we clearly saw all the fixing inside the building. When we tried to wash our clothes, the other guy who is at the front desk said all the machines were being in use, even though we saw them empty, and then he said:"If you know how to use them, then bring your clothes". Lastly, there is no A/C so you'll have to ask for a fan, otherwise this studio will be too hot for you.
Overall, it's an "OK" place if you plan to stay 1 or 2 days, but certainly I would not recommend this place if you're planning to stay longer than that.