I've stayed in a few places around Beyoglu and I'd recommend this the most. The location is perfect: you're close enough to the main high street for it to be convenient, yet far enough away for it to be quiet. It's set off the main road so foot and vehicle traffic is not as intrusive as it is elsewhere.
Enes is very helpful as well. He helped me out with PTT when I wasn't even checked into his place.
The place itself is unique. It's a basement level apartment with a window to the outside world, and although I was alone it's easily big enough for a couple.