The apartment is perfect for one or two people. It was very clean and Birkenstraße is a subway with really good connection to everywhere in Berlin. I would always come back :)
PS: I think the apartment is especially nice when you want to have a little more space as in a hotel room for example if you have some zoom meetings and are bound to stay in the flat for a few hours. You can make yourself your own strong coffee and are not dependent on hotel breakfast hours.