Fantastic few days - flat is gorgeous and furnished to a very high standard. Great location - about 5 mins walk from Istiklal Avenue. Kicker was the massive balcony, which was a lovely place to relax in the late afternoon sun after a long day's sightseeing. I think probably the only point to note is that it's on the top floor, up 5 flights of stairs, and without a lift, so maybe wouldn't be the best choice if you have mobility issues.
Yaprak was a great host and went above and beyond what you'd normally expect. She organised my transfers to and from the airport, as well as the delivery of a wifi hotspot so I could connect to wifi when out and about. She also sent me an 8 page list of recommendations on what to do. Whilst I obviously didn't have time to try all of them, those i did were amazing!
Highly recommended