This is a small establishment in the "old town", about 5+ minutes walk from the Blue Mosque, Hagia Sophia, Basilica Cistern, Mosaics Museum, Topkapi Palace. And about a zillion restaurants (but the street the hotel is in is small and quiet). In 10 minutes you can walk to a tram stop and catch a tram to where the ferries are at Eminönü - or go on foot in about maybe 30 minutes. The Grand Bazaar is also within (longish) walking distance. So the location really can't be beaten.
As everyone else has said, the staff are really friendly (hello Esin!) and the rooms comfortable and spotless. Our room was small but we managed to find enough stowage space for all our stuff. The wifi worked fine. (And yes, the spiral staircase is steep, but we're over 70 and we managed it!)
What marked the breakfast out from some comparably-priced places we stayed at in other cities was that there was protein (boiled eggs, cheese) and wonderful sliced fresh fruit - as well as rolls, tomatoes, cake, nutella-equivalent, and a lot of Turkish savoury dishes. One may use the kettle from lunchtime on.
A tip: In our experience, bathrooms in continental Europe often smell a bit "drainy" - unless the drainhole in the floor has been closed up. We found that putting the wastebin over the drainhole helped a lot with that. (NB the bathroom was spotlessly clean.)
The staff are all women, but Esin arranged for a young man to be on hand to help us take our luggage downstairs on the morning we left - there's no lift. (When we arrived and checked in early early in the morning we left our stuff at the front desk, and by the time we reappeared later in the day it had been taken upstairs for us.)
All in all we thought it was a very good place to stay, and excellent value for money. We have no hesitation at all in recommending it!
The hotel arranged for us to be picked up at the airport - we arrived at 5am so were very glad of that, even though it wasn't particularly cheap.