I stayed here for 2 weeks and absolutely loved it.
About the flat: A beautiful, thoughtfully designed flat. Clean, calm and welcoming interiors which have been freshly decorated. Well stocked kitchen, sharp kitchen knives (this makes such a difference!), comfortable bed, double glazing, good heating system, great pressure on the shower. It was also very peaceful, overlooking various tenement gardens. I brought my bike with me and there was space for it on the first floor landing of the building.
I have no complaints about the flat at all.
About the area: There are quite a few supermarkets around which makes food shopping easy. Great restaurants and cafes in the area too, and a short walk/bike ride into town. You are so close to Arthur's seat here, where I walked most days. Newington is great! I was staying up here to house hunt as I'm moving to Edinburgh, and decided to live in this area based on enjoying my stay so much.