I stayed one night at Nihat's place. Our communication worked very well so I found it easily and during the stay he was very helpful. The apartment is very central and close to the Taksim area. I took the Airport Schuttle to the Taksim Bus Station (not directly at the Taksim square). It takes 10-15 min with luggage to get to the apartment from the bus station. From the Taksim square to the apartment it's an up and down path (but that is normal for Istanbul) which can be heavy with your luggage.
But when you have arrived at the apartment it's quite and cozy. Had a wonderful week in Istanbul. Thank you very much