The place is lovely! The pictures don't make it justice to be honest. It's a very modern, tidy and confortable place. The bed is just amazingly comfortable and you have everything you need (including nespresso capsules).
The only not so great thing is that the flat is about 30 min away from the city centre by train, which is not the best if you want to do touristy stuff.
We didn't have the chance to meet Rainer because he was on holiday but he sent someone to give us the keys and he was very helpful on the phone.
I would recommend the place is you are looking for a local experience and lots of confort.