We have been very comfortable at Kalen's house. The arrival was great, Kalen has been very kind and his instructions about arriving at the house were great, very easy to find it.
He recommended us some places and did a free tour around the city.
The house is well located, you can arrive to the main places by walking. It's near the port so you can easily take the ferry to visit the Asian part.
The house is quite old so for example the shower is next to the toilet and sink and you will wet all around but water is hot, the shower works and he left something to clean and gets dry very soon.
I would also say that I would use ear plugs at night because you will listen to the Iman calling for praying and some boats because it's close to the port. Anyway, we slept very good, the bed is comfortable.
It's been a pleasure stay at Kalen's house and if we come back to Istanbul we will chose his house again.
Thanks Kalen!