We really enjoyed our stay at Umet's apartments. We ended up extending our stay by a few days and stayed in two apartments. The location was fantastic, right in the middle of Kadikoy/Moda, I think the bets location in Istanbul. The ferry to the Europe side was easily accessible and a great way to start and end our sightseeing days.
The apartments themselves aren't big but comfortable thoughtful spaces and the AC works well, you will need it if you are staying in the summer time.
Bulut our host was fantastic, communication was fast and he gave us everything we needed.
If we come back to Istanbul again (we think we will) we will be staying here again.