Alev was really nice and helpful for us. She showed us some great restaurants and even booked us a taxi in the middle of the night.
The apartment is very nice. It has everything you'll need. And it is really close to the main shopping street of Istanbul, and the nice restaurant/bars.
We've walked to the main tourist attractions from the apartment, within an hours walk, you can see everything.
There is one slight drawback: the bedroom is located street side. Istanbul being Istanbul, it can be quite noisy at night. But that is probably the same story everywhere in that city. I slept through it, my husband didn't.
If we come back to Istanbul (which we most certainly will), we would stay again at Alevs.