The place is beautifully located and has a fantastic layout for being in the city. I want to break up my review into several pieces to better explain the place (all ranked out of 5). Just so you know, we stayed for 6 weeks in Erkin's place out of the 11 weeks we stayed in Istanbul.
Erkin as a host - 5
He's really flexible and friendly. He responds quickly on whatsapp and was great to chat with. He speaks english well so there weren't any barriers for us.
Location - 5
The place is so close to so many things and is in a really hip neighborhood. Loved staying here in comparison to other places we stayed while in Istanbul. The front room does get a bit noisy with the bars downstairs and the bedroom hears the dish washing from the cafe but it's manageable.
Layout - 5
The double high ceilings make this place feel even larger than it is. Really was incredible. And the bathtub was such a nice perk!
Cleanliness - 0
Erkin is a bachelor. The place was disgusting when we got there. I would HIGHLY recommend getting a cleaning crew to go through before you do. My fiance and I spent the better half of a week cleaning. Hoping calling him out here prevents any of you from dealing with dirty dishes, molding bathtub, a sticky kitchen and blackened floors. Also be prepared to sift through dozens of random plates, pots, and cups to put together a useful set of dishware. He's the type of guy who uses ALL of the dishes in the house before he catches a clue that it's time to do dishes.
Amenities - 3
The space is labeled as "antique" which is a cop out for someone who is to cheap to properly renovate his place. The place is in dire need of some TLC for the doors, windows, floors and kitchen cabinets.
Overall Value - 3
The place is incredibly expensive in comparison to the standard of living you get. It is well located and spacious, but you'll have to ask yourself if that's worth putting up with the other bits.
We did really enjoy our stay. It just took a bit of unexpected effort on our end to get the place clean and somewhat organized. I would bet you'll be hard pressed to find an apartment with a better layout than this one in the city. I would recommend highly, just be cautious with the cleanliness expectations (especially now that COVID is a thing) and the state of disrepair in the house.