The Old Waverley Hotel is located on Princes Street, in the heart of the city. The first thing I noticed when I arrived was the overwhelming smell of soap in the stairwell, lobby, and restaurant / bar (soap shop Lush is just next door) and although it could smell of worse things, it can become a little overbearing, especially while eating.
I stayed in a twin room with windows overlooking Princes Street Gardens and Edinburgh Castle (so things could get a bit noisy at night time, and as I was staying around the Christmas period, there was a funfair taking place with thumping music and screaming children until around 11pm). The room had all the essentials including tea / coffee / biscuits, television, and a nicely sized, very clean ensuite bathroom.
Like much of the other accomodation in and around this area, it provides great access to all the tourist spots, bars, and restaurants; the city sightseeing bus tours are just across the road, as is the Scott Monument (climb to the top and get a certificate!). A 10-15 minute walk will bring you to a cinema and the Edinburgh Playhouse, and another short journey will lead you to the Royal Mile and it's numerous shops and museums.
I would highly recommend The Old Waverley; fairly priced, very friendly staff, and a location that cannot be bettered.