We've stayed in about 30 different VRBOs over the years, in multiple cities, and this was the nicest. The view from almost every room is better than any hotel in Istanbul, and you have to see it to believe it. It looks good in the pictures, but even nicer in person. The layout and furnishing and kitchen/bathrooms are all clean, modern, and attractive. Rooms were all warm enough in winter, which is lovely.
The location is excellent: close to the tram, the funicular up the hill to Taksim, and many shops for food and wine. Good coffee nearby at Just Coffee and Michelin ranked Topaz is up the hill and 5 minutes walk.
The only thing that might dissuade some is that it is on the fourth floor, and no elevator. Not a big deal in my view: you will do far more climbing up and down the steep streets!
The hosts were lovely: both Tuna and her husband were welcoming, communicative and responsive. Nothing to do with the apartment, but at one point the water service was interrupted, and they responded right away and kept us informed of what the city was up to.
If available, we'd never stay in anywhere else in Istanbul again! Although good for a family, it was also perfect for a couple and very romantic.