For me, the standout features of this apartment are 1) location, location, location, and 2) thoughtful extras provided by John (the host).
First, location -- it's tough to find a better place to base your DC visit from. A block away from a metro station, and a short walk from the US Capitol meant that we didn't have to work too hard to see everything we wanted to see.
Second, hospitality -- after a long day of traveling and getting in late on a Saturday evening, the last thing I wanted to do was go hunt down dinner at a restaurant. I wanted to relax for a few minutes and recharge, and I was really happy to see that John had stocked the fridge with soft drinks & beer, muffins, bagels, etc, provided a bowl of fruit and another bowl of miscellaneous snacks. This was *exactly* what I needed at that moment, and it was so welcome. We were instantly in love. Digging in a little deeper, we found that John had also provided a packet of information about local attractions, including restaurants and small grocery stores within walking distance. He even provided some smartrip cards for the metro!
Overall we were very happy with our stay, and we would happily stay here again if we were to visit DC again. Best experience I've ever had with AirBNB by far!