The location of the apartment is perfect; it's literally just one block away from Istiklal Street, 2 blocks away from Taksim Square (both the sight seeing spot and there metro station); it's also a couple blocks away from a major bus stop with a lot of bus lines.
Istiklal Street is one of the most important street in Istanbul where all the big brands are. H&M is about 3 minutes walk from the apartment. There are plenty of restaurants, supermarkets, pharmacies and bars within steps away. Some of them open 24/7, even during the lockdown in February and May. Location wise it doesn't get more convenient than that.
Ergül's a nice host. He also has a few other ensuite apartments in the same building besides the one I stayed in.
The apartment itself is neat and clean. It's quite spacious and well equipped as well, fit for a long term stay. The king size bed is comfy and it's big enough for more than one person.
I would like to stay in Ergül's listings when I'm in Istanbul next time, and I really recommend it, for both short and long term stays, and especially if it's your first time in Istanbul.