My first time in Istanbul and I stayed at the Medar Hotel. Overall it was a positive experience, decent clean hotel room, with routine cleaning, and friendly staff. Some of the staff also speak English so that can help international travelers. The hotel's location is near Istiklal Caddesi which is nice. The photos of the room are pretty accurate. They serve breakfast at the top floor from morning to afternoon. The building is secured with a numeric keypad and your hotel rook with a room card.
The check-in/check-out process was also easy. It's a good safe place to stay, because your near Istiklal Caddesi do expect some street noise. This isn't an exciting party hotel, but a hotel that is decent, good location, clean, and with friendly staff.
One thing I would recommend is the staff be more open about sharing travel tips to first time visitors. Tips on avoiding common Istanbul scams, how to best get around the city, and perhaps places to check out, etc.