My wife and I stayed at the place for 3 weeks in February and were happy.
The location is absolutely amazing! Kai, the owner, is a great guy who speaks English perfectly. It's can be important for the tourists who travel in Turkey for the first time.
The bathroom is pretty big and the toilet is clean and comfy. The bed is super comfortable.
It might be noisy at night but those are the real sounds of Istanbul. If you want to feel the atmosphere of the ancient city that's it.
If you happen to be stay there in winter you are lucky because the place has its own heating system and it's really warm inside, which is a big luck in the old city.
There can be some smell of dumpness but once the bathroom's door is closed we didn't have any problem with that.