Good for the low price I have paid. If properly refurbished could be much nicer but I guess would be more expensive as well. You would have to use the ferry or buses to get anywhere really, the ferry is quite close indeed, the only place you can get with it is Sirkeci (quite central). Taxi from the main airport takes longer to the Asian side.
Quite convenient if going to Buyukada island.
I've been quite a bit paranoid regarding the earthquakes and what I've read is the Asian side is on a solid rock while the European is sand-rick, also the house is only 2 floors, so probably a bit less dangerous in case of an earthquake. Very good place if you're concerned and OK to sacrifice some comfort for alleged safety :)