A great place to stay if you want to be in the middle of things. You are at the top of the Royal Mile, just steps from the Castle entrance. You can walk everywhere and see much of the city. There are wonderful hikes close by too (we did Calton Hill several times, Salisbury Cragg, and Arthur's Seat). There are excellent restaurants all within walking distance.
The check-in process was easy and the host responded promptly when the toilet in the main bath started leaking into the shop below on our second day there. A plumber was dispatched and after a couple of hours of work was able to correct the problem.
A few notes that might be helpful for you if you are considering staying: Because you are in the middle of things, it's quite noisy late into the evening and during the night so bring earplugs if you are a light sleeper. The staircase to get in/out is very steep and narrow so it would be difficult to navigate if you have mobility issues or knee trouble. The second bathroom is so small it would be hard to fit if you are tall or large in any way. There is no dining room or table to sit at and the kitchen is not really set up to cook much so definitely plan to eat out--at least for dinner.