We stayed at Kevin's house for two nights while we visited Washington DC. The space was perfect for our family of six.
The good:
The house was spotless and sparkling when we arrived. The neighbors were friendly (one even helped us jump our car when the battery died). The bed was the most comfortable I've ever slept in!
The not so good:
This house is located far enough from the National Mall that you'll need to take one or two busses and/or a train to get down there. If you're not familiar with how DC public transit works, this will likely be a struggle for you like it was for us. We ended up walking more than a mile at the end of our day because we couldn't figure out how to get home otherwise. This is no fault of Kevin, of course, but if you are in town as a tourist, you may want to stay closer to the National Mall or spend time studying bus routes ahead of time.
The other trouble we had with the location was that the neighborhood was very noisy. Police cars sped by late at night and the neighbor was honking his horn over and over at 5:30 in the morning. Not a very relaxing was to spend a day of vacation.
Overall, Kevin's place was great. He was quickly responsive to needs and questions we had and we felt comfortable and safe in the house.