We spend a month living in Mehmet's apartments in Istanbul. Compare to other offers in the area and around the city, I'd say Mehmet's place is the best option by price/quality ratio.
Apartments were exactly as they were described and well-prepared for our visit. Ideal place for two-three families living together or family with couple of children. Furniture and kitchen staff are not ideally new - but everything works fine. Also there are a lot of workplaces (tables) so we could comfortably work. And one of the most important points for us - stable WiFi, what (as we found out later) is the real differentiator for Istanbul (usually quality of connection is not really well).
Apartments literally in 2 mins from dozens of cafes of Istiklal area, but remember that Istanbul is a very noisy city and if you live in this area, you accept permanent noise around (or take earplugs :) ). If noise is not a problem for you - you'll like this location a lot, since it takes less an hour to visit anything from Taksim square till Galataport. Also a bus stop is right in front of apartment, so you can easily reach out Golden Horn (20 mins) or go to Sultanahmet district. Underground/metro station is on Taksim square - so it is also pretty close if you want to go far away :)
Mehmet is a perfect host, he was very responsive - waited us late in evening since our flight was delayed, and allowed us to have one extra hour during check out.
We were really happy to find such a good place for our long stay in Istanbul!