Excellent two-bedroom accommodation in lively Şişli, especially for long-term visits. Very close to pharmacies (eczane), exchange offices (döviz), a grocery store and two supermarkets (look up Carrefour and Migros). Cevahir Mall is within walking distance (no need to grab a cab unless you're carrying a bunch of shopping bags!). The apartment has a powerful air-conditioner, plenty of storage for household goods and groceries, and a washer and drying rack. There's plenty of closet space too, so no need to live out of your suitcase for your entire stay. Finally, the price for long-term stay was affordable, and well worth it for the kitchen. I'm sure you won't find a better deal with hotels.
A few cons were:
1) There was no hand or dish soap, no detergent, and no toilet paper or napkins, so you do have to come prepared to shop at the grocery store or supermarket to stock up for your stay.
2) The TV didn't have a lot of channels, and the only English or non-Turkish (Arabic) channel was the Al-Jazeera news channels. So don't come expecting Netflix readily installed. It's not a smart TV, though you might be able to cast your favorite shows and movies to the television. As I didn't try it, so I can't give a comment there.
3) The neighborhood of Şişli is a little further out if you're planning to tour the city (near the Fatih and Eminonu districts) and see sights like the Sultanahmet Square, Grand Bazaar and Spice Bazaar, Topkapı Palace, etc.
All that being said, I would still highly recommend this apartment. The pluses outweighed the cons for me.