I couldn't've stayed a better place in Istanbul than Emre's flat. I was there for a conference and my friends and colleagues were all staying in fancy hotels in Sultanahmet and Taksim. In comparing experiences we all found I'd made the best accommodation choice.
Why? First, the location. This is not a touristified area. People were genuinely friendly and polite when I approached them, even though I spoke no Turkish and hardly anyone spoke English. While my friends were harassed for money as they walked out their door, I walked out to a charming street of local stores, including a greengrocers just across, and a traditional bakery 20 steps away. I walked down this street at 3 am in the morning and felt perfectly safe.
The second reason it's great: the hosts. I didn't meet Emre, but his mother and brother live upstairs from the flat. The flat is separate: I had full privacy and saw very little of them, but they made it very clear that they were there for me if I needed anything at all. I arrived from the airport at 3 am, yet they let me in. When I left, I needed to get to the airport fast, Emre's brother helped me find a taxi and negotiated the price for me. Emre himself, whom I arranged the stay with, was quick to reply to my emails and gave me all the info I needed.
So: about the actual flat: it is clean and comfortable. There are actually 2 bathrooms and a third toilet. It is not bling-bling, but homely and well-equipped.
But it may not be everyone's idea of the perfect flat. If you need to be able to speak English to everyone, you might find it difficult living here. Also, restaurants in this area do not serve alcohol. As a woman I noticed that most women in this area covered their head. I did not feel like I as treated badly for not adhering to the dress code, and I wore my usual outfits (jeans & sweater). However if you're a woman who wants to feel free to walk out the door with cleavage or bare legs showing, that might not feel comfortable here. But I don't know. As I said, I didn't feel like people would treat me badly for my appearance.

In short: I felt lucky to be staying here. If I plan another trip to Istanbul, I'll contact Emre immediately to ask if his flat is free.