We stayed at the location for 5 days in December 2021. It is a nice apartment in the very centre of Istanbul. Nebi met us in the apartment, explained everything and handed the keys.
The apartment may need some time to get heated (if no one stayed before you and the heater was off). The first night was a bit cold but then it got better. One of the rooms had a draft from a window, but Nebi fixed the problem.
WiFi was available everywhere in the apartment but was a bit slow.
If you are using public transport be prepared to walk long steep up-/downhills. This has nothing to do with the apartment itself, but this is something to keep in mind if you are traveling with someone with reduced mobility. You also have to take steep stairs to enter the apartment.
Nebi is a nice person and he replied quickly when we had questions.
We enjoyed our staying there.