Dan's apartment is perfectly located close to everything you need to see in DC. It has all the basic amenities and is well equipped. The shower is great (both pressure and temperature wise) and so is the WiFi.
Few things to note: the apartment only has a spring bed (and it's quite small), the AC is extremely noisy (but works great) and you can quite easily hear the neighbors in the corridor.
If those aren't deal breakers then I would highly recommend the apartment for you. it's perfect for a short stay and Dan is an exceptionally helpful and communicative host