I very much enjoyed my 8-day stay at Hasan's place in Taksim. I came in late August and Istanbul was hot, but Hasan's apartment was relatively cool. I enjoyed having the windows open and encourage air flow with the fan. Everything was clean.
During my stay, Hasan was a remote host, but he stayed in touch and was communicative, generally able to respond in about 12 hours time if needed.
Things are pretty quiet in the neighborhood from about midnight to six am. But before that, you can expect somewhat loud music playing at neighboring venues. Since I had just arrived from 10 timezones away, my earplugs did the trick and allowed me to sleep through it.
Hasan's internet and Wifi worked great! Speedy download of > 25 Mbps. Definite plus. I was able to work and study at the kitchen table. The apartment is so close to the Taksim Square Metro station. I love the Taksim area. There is a convenience store/market nearby for basic items. The street approach off of Taksim Square is a rather steep hill. If you are elderly or mobility challenged, this might make it difficult to come and go.
Note that the window screens aren't a tight fit, so some mosquitoes do get in.
Overall: great place, loved my stay there, and hope I can visit and stay again. Thansk Hasan!