We love istanbul greatly because we stayed at Seyda's place for 5 nights.
Location is good and convenient, close by the Osmanbey subway and also buses are just around the corner.
The flat itself is fabulous and very very clean. We feel like completely at home and we cooked dinner almost everyday at home.
Seyda is always here to help as she is just living downstairs. She told us about the local flea market which is just nearby the flat and we love it very much.
BUT BEWARE, the flat is huge and spacious. So, personally I would say it may be too big for a couple only. We stayed there as 4 people and we found it it's perfect for us. Even a few more people is not a problem if someone do not mind sleeping in the living room.
Definitely a very very good experience for us.