Elvan's apartment is located in residential alley but very close to the main road. There is everything you can possibly need from small markets, cafes, local restaurants and even barbershops. The area is not touristy at all, but just about 10-12 minutes walk from very touristy Taksim. I returned home around midnight and never felt any kind of safety concerns. If you are bringing in a large / heavy suitcase, just bring the taxi directly to the apartment to avoid the short hilly stretch.
The apartment itself is very clean with a spacious guest bedroom and common area, well equipped kitchen, clean bathroom and a big outside patio. The bed was very comfortable and I slept well.
The best part was obviously the host herself. Elvan provided with very accurate details on how to reach the apartment. I arrived two hours earlier than I had originally hoped for and she showed up in less than 30 minutes from her work to let me in. She makes one feel very welcome and comfortable and she means it when she says "this is your home now". I felt as if I was visiting a friend. As a local, she is quite knowledgeable about Istanbul and it's daily life. She advised me to avoid Taksim area one day due to police barricade and interrupted metro service.
Bonus: Elvan's adorable cat Ponyo! She is friendly but low key. She'll hang out with you if you want but won't bother you otherwise.
Overall, I had a great stay at Elvan's apartment and I will definitely recommend this place to anyone looking for a place in non touristy area with some local life.