Was my first time using Airbnb and being in DC, I absolutely loved it. Great place and beautiful neighborhood (it's in the Eastern Market area). The flat was very well kept and spacious. They were also very sweet and gave me an extra blanket.
The flat is a couple of blocks from the Metro, Capitol, and Supreme Court. You can also find a lot of places to eat and drink in the neighborhood. Lively enough so you are alway entertained, but never out of hand like a college area.
I was working a lot so my only regret is that I wish I had more time for recreation. I'm definitely booking their place again when I come back.