To begin this will be a very honest and candid review. I'm giving 5 stars not for the accommodation per say - rather the host Mekhann made this as such.
I will start by saying that I believe Airbnb does not offer simply a 'washer' inclusion in terms of amenities, and rather gives a 'washer/dryer' option. I was under the impression there would be a dryer in the unit given this amenity as listed (i.e. washer/dryer). There is unfortunately no dryer in the residence. You'll need to use a drying rack to dry your clothes. Given the fact there is no balcony you'll have to spend the limited space inside finding an area to dry your clothes.
Additionally, this was a very quiet part of Istanbul which was a bit surprising considering how a 4 minute walk takes you to the heart of the Ortakoy where it's very lively, busy and quite noisy. Some things of additional note regarding the accommodation: the bed is very stiff and not all that comfortable, and the couch is just as stiff and even less comfortable. If you're like me and like to watch TV to fall asleep, you'll be in for an unpleasant time trying to watch a 32" TV from a good distance away. That isn't the worst of it though: the blinds do a very poor job of blocking out the light and so you'll basically be stuck with a very discomforting background lighting effect while attempting to fall asleep to some TV at night.
If you don't watch TV to bed, then you're good to go as he has installed a curtain system that basically blocks out this very annoying lighting from the outside street.
Now I'm not sure if this is just an issue with the particular unit I was staying at or an overall issue with Turkey's plumbing, but the hot water basically cycles on and off in the shower. You'll need to turn the shower head away every 45 seconds for a short time while it becomes unbearably hot. This made showering a pain.
Lastly, the unit is actually considerably smaller than you might expect. It's a studio-style apartment, but it simply gave you little to no 'breathing room' so if you're the claustrophobic type I wouldn't recommend it (especially if you're tall. Anyone that's 6' 3" will legitimately have to duck his head while walking most of the time. The ceiling is legitimately RIGHT there)
However despite all these inadequacies the host Mekhann was very gracious in everything. Very communicative, understanding and will attempt to make you as comfortable as possible. This is I know to be the case. I locked myself out of the apartment at one point - he had a locksmith there in 15 minutes flat. I asked if he had a fan, he had a brand new one delivered and already assembled as soon as I arrived. I even had to leave the country early for an emergency and end my stay several days early; he graciously provided me with a refund for the remaining days as well as wished me well.
For that he gets 5 stars.