We stayed a week at Greg's apartment, and had a fabulous trip!
First, the apartment was in a fabulous location. Although the street itself was quiet (even on New Year's Eve!), it was only a few blocks away from Dupont Circle. We loved having a parking spot as well, though it was sometimes a bit tricky to get out of the spot (a car with a backup camera would probably have no trouble, though!) Also, I don't recall it saying this on the listing, but if you go around the back, it's a private entrance.
Second, I really loved how well-stocked and well-labeled everything was. We never had to go searching for something / tried to figure out the rules, because everything was labeled right there. For instance -- there was a note by the trash cans explaining where the cans were and what the policy was (no need to take things out before check out, but if you did, here is where they were); the light switches for the hallway lights were labeled (super helpful!); in the bathroom, there was a note that if we were traveling with little ones, there was a child-proofing lock under the cabinet that we could use so that our daughter wouldn't get into the cleaning chemicals...
Everything else was exactly perfect -- beds were super comfortable, kitchen was well-stocked (including with cooking spray, eggs, butter etc), it was very clean, plenty of towels, it was easy for us to child proof it for our 2-year-old, there were games, books, and extra kid-friendly supplies like a high chair, booster, Pack 'n play... Greg really made it easy to stay a week.
FYI that the apartment was on the 1st floor. We did occasionally hear some noise from the apartment above (floorboards, TV) -- it was never an issue because there are quiet times posted, and the upstairs apartment was always respectful of noise even outside of those quiet times, but just FYI if you're not used to having anyone living above you.
We would return again in a heartbeat, either here or one of Greg's other properties.