The area is 5 minutes from Istiklal and a slight bit sketchy, but not dangerous. There's a nice market on Sundays just in front. It sits on a 5th floor (without elevator), but we didn't find it too cumbersome. The building itself is old so a bit of noise from outside / neighbours.
The apartment is very luminous and has most things you will need. The host was very responsive whenever we asked for something (additional linens, a coffee maker) and fixed the shower when it gave us problems.
Enough space for working out with a yogamat and a nice desk for remote work. WiFi works generally well. Appliances are all new, but beds / mattresses and the bedroom furniture are dated.
Overall a good experience for two people working remotely for a month in Istanbul.