I only stayed for one night, but had a great time. Mehmet is a kind and intelligent host who also speaks good English which is not natural in Istanbul.
Don't expect something fancy, but an apartment in which a guy (with some engineering experience) invested time, thought and heart.
The bed is big, the blankets comfy and the heater's working great. I didn't try the kitchen out, but it seemed to have everything. There' also a washing machine for free and Mehmet prepares some snacks and information about Istanbul for you.