We had a pleasant stay at Tolga's place near Taksim. Although a little hard to locate at first, once we had settled in we enjoyed wandering the streets nearby to discover local cafés and shops. The main attractions in Sultanamet are a quick train ride away or a nice walk under the galata bridge (if it's not too hot out.)
The only complication was the fixed time for check in and check out. We had to find alternative arrangements for our bags. As well, we were charged a very small fee for the AC it being the middle of summer and the electricity being expensive here.
Overall, I strongly recommend this apartment to anyone wishing to enjoy the area near Taksim and Galata Tower.