The location of Yaşar's apartment is excellent, really close to Taksim square and Istiklal street. The stairs in the building are very narrow and there's no elevator, so you should avoid bringing big suitcases. Being in the centre, it would get a bit noisy in the evening but that wasn't a big problem for us.
On the other hand, the photos of the apartment don't reflect the reality - the apartment was dirty and should be renovated soon, at least the walls should be painted and the whole place needs thorough cleaning. The bed (mattress) was noisy - you could hear wires and springs every time someone moved on it.
Yaşar was a friendly host and he let us leave our luggage with him after check-out, for which we are grateful.
Great location, good communication, poor cleanliness.