My partner and I stayed for a long weekend in January and had a great time. The flat was in great condition, really homely and had everything we needed e.g. shampoo, shower gel, foodie bits in the cupboard. There is a co-op a few minutes down the road so it was really easy to get food and not too far to carry it! The flat doesn't have TV, which isn't a problem when you're out exploring, but on those occasions where you do fancy monging out, I would suggest bringing different games and we found using the radio was fun too!
We soon learnt that the location was great early on! We started exploring by getting the bus from straight outside the flat into the city centre and then realised that the 20-25 minute walk to Royal Mile was manageable so did this more towards the end of our stay. I would recommend the walk as it goes past Holyrood Park and Scottish Parliament and they're great to look at. The underground vault tour at night was a fun experience and the current exhibition at the national gallery is really cool so I would recommend trying to visit there!