Alex is a good host who is quick to respond to message and offered good and very clear directions to the address.
The apartment is centrally located - a 15 minute walk to the central station and very close to key bus routes. Also a 10 minute walk to groceries. The bathroom is cramped, and the kitchen smallish, but this will serve as a good launch pad for your Berlin visit especially if you plan to be going out most of the time. As with the vast majority of the listings on AirBnB, 2 bedrooms means the common space is the second bedroom.