The apartment is fully consistent with the description but waking to Hagia Sophia is about 10 minutes, not 5. The Grand Bazaar is closer. There are several grocery stores right next to the house. The elevator is very appropriate after walking through a huge Istanbul. The Internet is quite quick.
Okan is a wonderful hoster. He helped us with all questions that we had. He ordered a taxi for 5 people from the airport and met us at night. When the boiler showed us an error and didn't turn on, Okan invited a technician and resolved a problem in a few hours.
I definitely recommend this apartment to a big friendly company.