Ahmet is a great host. Very polite, accurate and willing to help.
Flat is exactly what you see on the photos, so you'll get what you count on.
It's located in about 10-15 minutes walk from Osmanbey metro station, which is the next one to Taksim. Plus it's on the same line where Vezneciler station is, from there you can get to most of the places of the old Istanbul, including Topkapi Palace.
The neighborhood itself is also great. You'll find there typical Turkish street food, some supermarkets and a few nice cafe/restaurants. I personally did liked breakfast and coffee in Ministry of Coffee, which is nearby.