Daniela's place is clean, new, and well-equipped, in a safe and quiet neighbourhood. Daniela and Vladimir were very accommodating, and even though they were out of town on their own vacation they were very responsive to our requests. They arranged for an early check-in, had a friend come help with a couple move-in things, and even purchased a fan to make things more comfortable in the heat.
We selected this place partly because of the bicycles but did not end up using them as one is a mountain bike style (rather than a city bike) and the other had a flat tire (which they tried to fix but unsuccessfully). However, the Vienna city bike system is fabulous so if you plan to cycle in the city, as we did, don't hesitate to use it. The closest place to get a bike is at most a 10 minute walk.
As others have mentioned, the apartment is reasonably close to the Palace but not close to the centre or other attractions. There are a couple grocery stores and restaurants within about 10 minute walk but just know that it is a very residential area, not a bustling centre of activity.