Our family (myself, my wife, and our 9mo son) stayed at Nicole's place for about a week while visiting family nearby, and we couldn't be happier to have found such a great spot. Check-in was seamless (all the locks are keyless), and the location (under 10min walk to Dupont Circle) was a perfect balance of convenience and quiet.
The building is quirky and on the older side, but very nicely maintained. The only drawback for our case was that it's up three flights of stairs and babies come with a ton of heavy accessories. Make sure you've got enough hands in your party for lugging stuff up there! The living room and master bedroom are both super roomy and carry kind of an old-world feel, and the kitchen and half-bath get surprisingly excellent natural light through their wide skylights. The second bedroom has 2 single beds and not a ton of space, but the common living space more than makes up for that. The kitchen is small but outfitted really well-- we leaned hard on the provided appliances and dinnerware to save money on takeout/restaurants during our stay and had no trouble at all. Our favorite feature was the in-unit washer/dryer in the half bath, which looks small and maybe not so new, but honestly works better than what we've got at home! Between having a little baby and also coming home sopping wet from a very rainy week in DC, knowing that hardworking W/D was waiting there for us was such a comfort.
A couple notes on the location: We were mostly in town visiting family on their home turf in Cleveland Park, so being so close to the Metro was amazing. Since we were often heading in that direction most days, we didn't get around to many of the great-sounding recommendations Nicole provided when we checked in, however the apartment is a very short walk to Firehook Bakery, which we visited way too often, and that's across the street from a nicely stocked beer/liquor store that we also visited way too often.
Last but not least, Nicole was a terrific host! She was totally hands-off from the start, but responded immediately to all our questions. She was super friendly and clearly cares a lot about the property. We hope to stay at her place again soon!