One word immediately came to mind: Charming! The flat was in an absolutely unbeatable location in Old town, in an old building with a darling inner courtyard. You are minutes away from everything - as described, Stephensplatz UBahn is only 5 minutes away! Even before you get to Stephensplatz, you will bump into scores of local restaurants and cafes. We tried as many as we could - Cafe Diglass, Cafe Alt Wien to name a few. You are around the corner from Stephensplatz and the Hofburg complex and easy walking distance (best way to see the city :)), from Alberstplatz and the Staatsoper.
The apartment itself was very clean, well appointed with comfortable beds. One of the neighbors practiced some opera-like singing a couple of the mornings, and this only added to the ambieance!
Andrei was very helpful - and efficient. He met us at the door, showed us the flat, and had already provided printed information to all the things we might need. He gave us restaurant recommendations and was very prompt with communication before we got there. Do pick this place for a vacation with character, easy check-in/check-out with a friendly host and unbeatable location :).