This is a really good option for DC with one exception, the neighborhood. The location is GREAT, close to the Capitol, short walk to the metro, grocery around the corner, however, the Potomac Gardens apartment project is literally right across the street. We spoke to the owner of the deli around the corner, Mangialardo & Sons (which is awesome btw) and he cautioned us to "be careful at night because it gets rough". So we were a little concerned at first, but in the end became really comfortable there and had no issues, other than a loud late night argument. So if you are skittish about the neighborhood this might not be the place.
Other than that this place is really good. Allen is fantastic and highly responsive. The property is quite old, and the wood floors are creaky, but we found that charming. The three bedrooms upstairs are very comfortable and the futon in the living room is passable if you need a fourth bed for a short stay.
The kitchen is well stocked with everything you need to cook.
The internet speed is decent if you are close to the router, but does not work in every room.
The living room is a little small for a family of 5, but we made due with the seating available.
The back yard did need some attention. The picture on Homeaway of the outside is not accurate as of August 2014. The back yard is overgrown with weeds and needs to be maintained, but you can still sit out there.
Overall we had a great stay once we got comfortable with the neighborhood.