We read all the fabulous reviews before we booked and Sebnem met our sky high expectations.
Rooms are simple and small, but hardly claustrophobic, and very clean. Breakfast food was plentiful, with lots of variety, most of it very good. The terrace is a terrific place to drink morning coffee or tea and plan your day. Location is great, within easy walking distance to Blue Mosque, Hagia Sophia and Topkapi Palace. Room rates are very reasonable--Consider that the Four Seasons Istanbul is barely a block away, and other than maybe a larger room, it's got nothing on this place.
Finally, the staff here make this otherwise 4-star a 5: They're super helpful with luggage, directions and all the other usual niceities. When I came down with food poisoning (definitely avoid the kebap plate at Pudding Shop!), one of the kitchen staff went out of his way to bring me a warm hydrating tea and ice when I could barely muster the energy to even talk. Everyone took a turn to check in and ask if I needed anything. Very much appreciated this!