At first, I was a little bit disappointed. The place is exactly how you see it in the pictures, but the kitchen was poorly equipped, and I received one single toilet paper after paying for one month. It wasn't perfectly clean. Also, there wasn't anything in the room for cleaning up. Just one destroyed and very old broom. The bathroom is also very old. Or it looks like it. However, This stay is in a great location: near Taksim square, and there are a lot of nice cafes and restaurants in the area (and many mini markets).
The host is very nice, flexible and always available. I arrived in the middle of the night and the check in was very easy.
The Internet connection was a pain: extremely slow and unstable. Unfortunately for me, I had to work, and it was hard. Istanbul is a city with many cafes to work from so I kind of solved the problem in this way.
The washing machine is in the building and it's pretty recent, but it's in a very uncomfortable position at the very last floor of the building in a tight place.
I recommend this place only if you are alone and don't need to work (and rarely stay inside during your stay). The price is decent (but could probably be cheaper, the place needs some serious renovations imo), and it's close to a top location.
I think that with a relatively little investment this stay could become one of the best in the area. It will probably improve over time.