We had a lovely stay at Kurt & Sabine's apartment. It's beautifully decorated, modern and elegant but also comfortable and welcoming. It's wonderfully located, close to lots of great restaurants and places of interest. It's a really nice area, and at Christmastime there's one market at the end of the road and another about a minute further along. Sabine was very nice and friendly, and quick to respond to messages. Check-in was easy as there's a reception desk in the entrance hall, and there was always a nice receptionist to welcome us home.
The only slight flaw is that the windows aren't very insulated, so there is a bit of street noise (but nothing that can't be solved with some earplugs), and also some coldness gets in that way (we were staying in mid-December though). Otherwise it's really quite perfect!