Staying with Eser was very nice. The hotel is located on a great spot just a few minutes by foot away from Topkapi, Aya Sofia and the Blue mosque. This makes it easy to reach and walk around. Close by you also have a tram stop, so you can easily reach the other sights. On the other side the hotel is located right next to school and they play songs starting 9am, so if you are planning to sleep late, it's good if you like music as well. Generally the location is quiet, but sometimes there are some noises from outside, but if you expect quiet and peaceful, Istanbul is not really your place :)
Other than that Maria, Ismail and Tatiana were very, very sweet and helpful. We wish them luck in all their endeavors.