I stayed in this flat for 12 days.
Here is my feedback:
Mehmet was always available and responsive. He responded to all my requests promptly.
When we arrived in Istanbul, the weather was very hot. The living room had AC but the bedroom did not. As soon as we let Mehmet know that the bedroom was too hot, he brought a brand new fan.
The flat is as described in the photos. It's not very large in size but it was enough for 3 persons. The flat was very clean and tidy on arrival, and the linen and towels provided sufficed.
The location is great, it's in the middle of two very busy and well-serviced streets. Osmanbey metro station was steps away, and it's just one stop away from Taksim.
The main thing we had a problem with, which brought down the quality of the stay is the bathroom. The bathroom is old and needs renovation, however, the main problem we had with the bathroom is the constant smell of sewage which we could not get rid off despite all attempts. I would happily return to stay in this flat if this issue was resolved.
Another issue we had, albeit not very significant is that the lighting throughout the flat was very dim. Which made getting ready difficult as the light did not suffice for using the mirrors.
According to the company policy (not related to the host), any extra services are chargeable. For example, there is a €20 surcharge for changing check-in/out time, plus €35 charge for cleaning/changing linens after 1 week's stay. In other words, don't expect any extra services unless you're willing to pay more.
Finally, I highly recommend Mehmet as a host. He was very helpful, nice and polite.