A great place to stay while in DC! Graham and Bear are great hosts, and they provide several amenities that most hotels would not. The apartment itself is comfortable and charming, and is ideal for one or two people.
Although a few miles away from the National Mall, the apartment is still within walking distance of Union Metro Station, so one can get around the city reasonably fast. Several nice restaurants and grocery stores are nearby too.
For any light-sleepers, I suggest making use of the earplugs that Graham generously provides. The apartment is located near a fairly busy road that may be noisy in late evening and early morning hours. This should not deter one from staying here though, for it is not as bad as some parts of the city.
Summary: A comfortable place also with easy access to food, drink, and public transit. Nearby traffic is occasionally noisy, but earplugs are provided if this becomes bothersome.