Stella's apartment was great for our trip for the Berlin marathon. It was comfortable when we took it easy at home, it was close to many restaurants and is close to public transportation to get to other parts of Berlin.
As the listing says, you can hear noise from the street from the bedrooms (mostly cars/trams). This didn't affect our sleep since we had a sound machine.
Check in and check out was simple. Stella was also very attentive when we had questions during our stay.