Our stay at I'zaz was absolutely amazing! The location is great (bustling neighborhood, close to the fish bazaar and shopping mile), plenty of good restaurants and bars in close proximity (5-10 minutes of walking) and in walking distance to the tramway which will take you directly to Sultanahmet.
I'zaz itself is a very nice house in a quiet and safe street. The rooms are nicely decorated and spacious (we even had a small balcony), and the lounge on the rooftop is really beautiful: it's open to all guests and has access to a small kitchen, food (cereal, milk, juices, etc.), and backgammon games.
As to the I'zaz team, we were truly treated like family! My mother and I stayed for almost a week and Hakan helped us with whatever questions we had, gave us a whole list of restaurants, reserved tables for us, and even helped us out with typically "girly stuff", such as mani and pedi places. The whole team was extremely friendly (Zeynep, the owner, always took time to chat with us, Nermin kept our room wonderfully clean, and Ali made sure that we felt safe when we came home at night). So all in all: I'zaz is not just a place you stay at in Istanbul, it's home away from home!