We stayed with Hakan&Turkan for 3 days, and it was amazing. The apartment has everything you need and is a great value for its price. It is very close to Galata, Taksim, Istiklal and all the historical places you would want to go (all about 5-15 mins).
Apartment is perfect for small families and it is furnished very well and with taste.
You should be ready that location is in an average neighbourhood without the views, the noise isolation is not very well. But we were still so tired from exploring Istanbul everyday, so it did not matter.
The hosts are very helpful, they helped us get transfer early in the morning to the airport which was of a big help.
Would come again to stay there.