We stayed here in September 2018. We liked the fact the mews is on multiple levels! The kitchen has a cooker, fridge, and dishwasher. There is a massive TV and Apple TV too and the wifi is great. Toilet upstairs and bathroom with toilet downstairs. There is also a washing machine and separate dryer, iron and board and hairdryer.
The mews is located about 6 streets (blocks) down from Princes Street. Its only 10mins to be on the main shopping street. We walked from here across into the old town too, its all easily walkable (we did sneak in a couple of Uber taxi's in the evening which works great too!)
Parking is free at night but on the meter in the day - its £2.90 an hour and only 4 hours in one location - the traffic wardens are frequent. My advice would be to stick your car in the Waverley train station at £17 per day.
For breakfast there are loads of recommended cafe's (Bluebird Cafe) within 5 to 10mins from the mews. You are also basically in Stockbridge so lots of posh shops and boutiques if you want something different from the Princes Street too.
Leith is 5 miles away if you fancy the seaside and a walk on the prom!
Would definitely stay here again - thanks Marie.