We stayed seven nights at Nezih's flat; Nezih is very nice and helpfull and his flat offers - besides absolutely stunning views on the Bosporus - everything you need for a trip to Istanbul. It is in the heart of the Beoglu / Cihangir area, which a) is very centrally located and b) has plenty of very nice coffee shops, bars and restaurants - which unfortunately also means that you may want to consider wearing ear plugs to have a quiet night, at least over the weekend.... The flat has relatively old furniture and the bed is nothing for people with back problems, as everything in the flat has quite some patina - and could need quite a good cleaning....
But, besides the criticism: Recommended!