I echo what everyone else has said about Ilhan's place - PERFECTLY LOCATED!
You are super close to many of the beautiful sights of Innere Stadt (old town) Vienna. Less than 5 minute walk to the Rathaus (town hall), about 7 minute walk to the Hofsburg Palace & BOTH the Art History & Natural History Museums. You're SUPER ideally located. Trains & trams are also close by.
Lastly, Ilhan is a GREAT HOST & his place is as homey as it can get - spacious, comfortable & luminous...
I would SURELY come back to Vienna & stay at Ilhan's place...