Erhan is a good and kind host and was quick with responses which was amazing. The apartment definitely needs a bit of an update, especially with the small window in the bathroom that doesn't close properly as it get chilly in the bathroom as well as lets smelly air from the outside sometimes (it didn't come from the building or apartment and it was only one night for a few minutes) However it still had things that were great such as a washing machine, hair dryer, extra towels and heating (for the winter). I would suggest bringing flip-flops for the bathroom since the door for the shower doesn't close properly so the floor gets a bit wet (it doesn't affect shower time though). The place is pretty clean. It is on the 5th floor so it was a bit of a hassle with heavy suitcases so it might not be suitable for seniors as there is no elevator in the building (i also fell down the stairs made of stone, my own fault of course but still be careful :) )
The location of the apartment is amazing as it is literally 1-2 minutes walk to Istiklal street and about 5-10min to metro. All the airport buses stop approximatelly 15-20 walk from the apartment which was great and easy to get to (they come every 30 minutes i think) I would definitely suggest staying in Taksim rather than in Sultanahmet because Taksim is lively even at 3 am in the morning during winter rather than the old part of the city where everything closes around 8-9pm. It was pretty quiet and safe around the apartment.
All in all we still had a nice stay and are grateful to Erhan for his hospitaliy and would recommend it especially if it gets updated a little bit :)