The location is amazing. it's about a 20min walk to Taksim, a 10-15min walk to the metro. It is near a main road with tons of buses that come on time and are clean. It is also located 10min away by foot from the Piyalepaşa Havaist bus that takes you straight to the airport. Every basic necessity is available within a short distance. Communication with the host was equally great. He really helped me with the essentials (where to get food, the instanbul kart etc...).
The apt itself is spacious enough. i didn't hang out in the apt. It was more a place for me to sleep. The bathroom though does have a muggy smell but the host did leave a spray. Either way, the cleanliness for me was sub par.
Do know that there are a couple of steep hills around that you will need to take until you became familiar with the area and discover the alternative. It is also right beside a school so if you're there during school days, you will be woken up M-F at 8am with a song.