The good points - Yes, it is a fantastic location. Located behind a street of restaurants (which we were advised not to eat along), and 5 minute walk to Blue Mosque and Aya Sofya. Breakfasts on the terrace overlooking the Bosphorus are lovely, though from what we could see, this is a common thing with a lot of the accommodation in the area.
The bad points - this would be enough for us to think twice about staying here again. Firstly, do not stay in the ground floor room. A lot of reviewers mention great rooms, but the ground floor room is not one of them. It is dingy, lacks character and feels suffocating. Furthermore, loud music can be heard late at night from this room. Secondly, while the family running the guesthouse are friendly and smile at you during breakfast, only the younger lady speaks English. This makes it too hard if she is not around and you have questions to ask. Thirdly, it was quite disappointing that an Airport Transfer, which was supposed to have been booked by the guesthouse did not arrive. Although the older man at the guesthouse was helpful in calling a taxi, it was a mad rush to the airport and we almost missed our flight because of Marmara's inefficiency.
I would only recommend this hotel if this is all your budget can afford.More