Safe and very convenient for the single traveller - my first time to Istanbul, my priorities were the historic sites of the Blue Mosque, Hagia Sophia and Topkapi Palace - on the map I could see they were nearby (the blue mosque is in the background of a photo taken from the terrace) - but on arrival I was rapt to discover I was right below that area - its a leisurely ten minute walk on a safe, busy street to get to the square.
From the square there is a tram stop, but I used the hop on hop off bus to get round and both the red and blue lines stop at the square. Also located there is the Istanbul Archeological Museum, a small bazaar, the mosaic museum, the carpet museum - and with the Grand Bazaar approximately 15 minutes away I spent the majority of the first two days less than 15 minuts walk away from the hotel.
The hotel itself is small, four floors and a total of 20 rooms, plus a top floor cafe with a terrace facing the mosque and a small balcony facing the Bosphorus Straight - the front desk was always manned and the staff were friendly and helpful - when I checked in I was told to be careful of strangers in the street offering hospitality (come check out this bar etc), it was nothing to do with the area, more just something that happens in Istanbul, it did happen and being forwarned I always had somewhere else to be etc, I appreciated the advice.
The rooms are clean, a good size with a small fridge, and the hotel is set back from the busy main street so its quiet and the neighouring buildings are small restaurants and a minimarket - really useful stuff.
I wouldn't hesitate to use Deniz Houses again - Istanbul is amazing, it was nice to have somewhere so convenient to everything I wanted to see, I felt safe and really enjoyed my stay.