First of all, Fatih is a great, great host. Always just an instant message away, ready to help or to give a local advice. It's like having a hotel concierge, just better :)
The place itself is very nice, and exactly like on the pictures. There were no surprises, what you see is what you get. Bed in the master bedroom is a bit on the hard side, which worked great for us. And the couch in the living room is really comfy - we had a lot of wonderful naps there :)
The water heater, fridge - everything works as it should.
The location. Ok, do understand that this is not a touristy place. Instead, it's a very nice and lively local neighborhood. If you are coming for the museums - maybe staying closer to the centre would work better for you (there are very convenient public transport connections, but it takes 30-40 minutes to get to the centre), but if you want to experience what is Istanbul - this IS the location to stay.
As I've said, the neighborhood is very lively and active. I think that there is more than a hundred different places to eat in the five minutes radius. Not an overstatement. The choice is tremendous.
Some recommendations: Try Urfa Kebap in Abooo Kebap, any juice or juice cocktail in the lovely Cennet Meyve Suları or have some simple fried fish in Ali Baba Balıkçılık - all on Mehmet Akif Cd, less than two minutes walking. And also try pide in Sürmene Side on Dereboyu Cd. - one of the best doughs I've ever had in any country.
But, really, just go anywhere there, it's all very nice. Don't forget to buy fresh bread, fruits, vegetables, and freshly fried nuts. All of that is about 50-70 meters from the apartment. (Also, ask Fatih, he gave us great recommendations).
Oh, and hammam is in the next building. Don't forget to enjoy it few times during you stay.
Metro, Metrobüs and large public transport stop is in 500 meters or so (for example, direct connections to the centre or Istanbul Aquarium and Aqua Floria).
BTW, one of the new Istanbul Airport busses (IST 4) stops there, so there is no need for the transfer, just take the bus from and to the airport, it's fast, comfortable and cheap (18 TL).
There is also a stop for the local small buses even closer (with a direct connection to the Marmara Forum shopping mall (2.60 TL).
Is it noticeable that I like the area quite a lot? :)
Anyway, to cut the long story slightly less long (believe me, I can go on and on): great host, great location, great city.
Are there any downsides? To be honest, there is one small one. The internet connection in the apartment is not very stable. Which makes it perfectly suitable for, say, Youtube or Netflix streaming, or the regular web browsing, but not very suitable for, say, voice or video calls (since there is a noticeable delay). So it is fully ok for the recreation purposes, but is a bit wonky to work. But I know that Fatih is already working on arranging a better connection. So, probably, this is not even valid anymore :)
Fatih, my friend, thank you very much.