The apartment is at a prime location in Sultanahmet. You can go to the blue mosque and tram station in less than 10 minutes. I loved Istanbul public transportation, you can take trams, trains, cablecars, ferries easily once you reach a station, it's very connected. The area is touristy, so main downside is that the restaurants near the apartment are expensive compared to other places (and some try to rip you off, so check Google reviews!) and doesn't have best quality food. Area is very safe for families.
The unit had pretty good Wifi. And it did have a washing machine (though I wish they put some washing solution).
Mehmet wasn't there to check us in, but his son and another person were extremely helpful. The folks helped us take the luggage bags upstairs to the unit. Very helpful when you have kids! Mehmet allowed us to check in earlier and was very flexible.