Güner & Güven are very available hosts.
When you make a reservation of the flat, they send you a document with all the details of how to get to the flat. We choose the option taxi and I think it was easier. Once you know the neighbourhood you'll be okay to find your way but we were happy to get there with a taxi.
The explanations writen for the taxi driver that Güner sent us leads to his office where he welcomes you very warmly. The flat is just a few meters away and you meet Güven who lives in the building and can help you if you have any problem.
The flat looks perfectly like the photos, and is clean. Free WIFI. We appreciated the air conditioned and the neighbourhood is quiet. The situation is really near Istiklal street but without all the noise and music.
On sundays there is a market down the building from early in the morning until late at night but it didn't disturb us at all.

If you send an email to the boys they'll answer very quickly and they are both very nice.

We highly recommend this flat if you are planning to visit Istanbul and do not want to stay where all the tourists are.