My husband and I stayed in Yusuf's apartment on our second leg of our trip to Istanbul. Yusuf was very quick to respond to all our questions, he made sure our two way airport transfers was settled prior to our arrival and even linked us up to go on a Bosphorus Cruise in ten minutes! (The cruise started at 10am, and we informed him only at 9.50am on the same day. This was AMAZING service!)
I would definitely recommend Yusuf's apartment to young couples or families looking for an affordable place to stay in Istanbul that is centrally located and accessible by public transport.