I stayed at Fatma and Hasan's for a month and I really liked both them and the place. They are great people!
I stayed at the top floor next to the terrace which was a very nice and relaxing start/end to every day. Along with that, the amenities provided did enable a long stay, like the small kitchen, washing machine etc. The neighbourhood is local but it is only a short walk out and into the very popular streets that lead to Istiklal Street and Taksim square. From there it is very easy to go anywhere in Istanbul. So the location is very good for exploring the city.
I highly recommend this place and I will stay here myself when back in Istanbul.