This place is good for the price and the location. It is a bit on the older side (not surprising given the location and age of the apartment building), so there was a slight dingy smell -- nothing that really bothered us. The location to the touristy parts cannot be beat.
I did want to make a note: when trying to find the place via Google Maps, type in the name of the location first, leaving off the unit number. Our app took us to the grassmarket nearby, which was close, but not exactly. This was a bit of frustration for us.
Additionally, make sure you ask for the guest guide book right before getting there. We got an old version which left off a lot of information and were a bit frustrated when we were trying to find the WiFi password/other information. The one they provided when we asked was very informative, but would've preferred to have received it before arriving since it was very helpful in finding the place (would've been nice when we were frantically wandering in the rain to find it).
Despite these minor inconveniences, we did enjoy our stay there and would recommend it to others.