We stayed at Mert's place for a week and it was even better than the description and photos. The location is great, 10 mins' walk to the airport bus stop and right next to Taksim Square. There are some hilly streets in the area, but this apartment is only about 50 meters down a hill, so you won't struggle for long :) We were planning on cooking, and from what we saw, it would have been very possible (pots, pans, utensils, dishes, at least one strainer, many Tupperware containers, etc - and they looked to be decent-quality), but the restaurants nearby were so delicious and cheap, that we mostly ate out.
We met Mert when we arrived and he seemed extremely helpful and genuine. He checked in (via message) every couple days to see if we needed anything, and we could tell that he really wanted to make sure that we had a comfortable stay.
The building has 3 apartments in it, all managed by Mert, and he has a reception desk downstairs - it is set up a bit like a guesthouse. There isn't always someone at reception, but when we texted Mert that we ran out of toilet paper, it was delivered to our door within 15 minutes, so that was pretty fast! We barely heard any noise from the other apartments even though we knew there were guests in one of them - great soundproofing. The cleaner comes every few days if you want, and (the most amazing thing) there is a free laundry service. We just left our bag of dirty laundry and got it returned to us washed and folded!
As promised, Wi-Fi is excellent and hot water is plentiful. The bathroom is very nice - way more modern than it appears in the photos - and the shower is perfect and heats up right away. The smart TV is great, and the balcony provides great views on a clear day. Heating works well. There are even little details like electrical outlets built into the bedside tables. In general, the apartment is very modern and cozy. Really happy we stayed here!!