I cannot imagine a better located apartment in all of Zurich - the views from the window are lovely and sights, restaurants, bars, museums are all only a short walk away. Recommend visiting when the Christmas markets are about, as the streets in the old town are simply magical and it's just a short walk to a giant Christmas market at the Opera House.
The apartment was clean, small and perfectly formed (with a comfy and very large bed). There isn't a kitchen sink or any real cooking facilities, but this was not much of an issue for us and you could always stay in one night to escape Zurich prices with a nice salad (also a takeaway deli with hot foods just around the corner).
The wifi was a little patchy at times, but fine for a bit of business and extended holiday stay. Chris and Blanca were very communicative, answering any questions I had.
Check-in is slightly complicated, as have to pick up the keys from a bar around the corner, but the bar staff were very friendly and had been fully briefed.