Mehmet's place is an oasis of coziness in the heart of the city. Very confortable and classily decorated. We'll definitely stay here again in our next trip to Istanbul. It is close to everywhere that matters. In a radius of 2 minutes of walk, there are many shops and markets, piers and a public transportation hub. You can take a ferry to Asian side, get on a tram to old city, or walk to Istiklal/Taksim in 15 minutes. And the place was extra clean and tidy.
Those were the pros, but there are a few cons. First, a parking problem exists, so if you insist on having your car nearby, think again. Also, no elevator. And lastly, because of the (great) location, it may be a little noisy in the summers. The insulation of the windows were perfect though. These were not problems for us at all, but YMMV.
Mehmet is a great host, caring and sincere. Lastly, waking to a view of the great big plane tree in the garden of the church across, with its crimson leaves was a delight.
Highly recommended.