Engin's house is perfectly located near Taksim Square. It is beautifully decorated and comfortable for a short stay. The apartment is on the 4th floor. We didn't mind the stairs but this wouldn't make it suitable for all.
The apartment doesn't get much sunlight so for us it wouldn't be suitable for a long stay. I am assuming that would be the case for most of the apartments in the area though.
We had an issue with cleaning not being up to our standards but when we informed Engin, he sent the cleaning lady (who was super sweet) within a couple hours which we appreciated.
The kitchen is missing some essentials but again no big deal for a short stay.
Overall it was a good stay and good value especially if you are trying to do all the tourist attractions. For us, however, after spending 10 days in Istanbul, we would stay on the Asian side next time.