I stayed in Nikola's apartment for a week with my husband. The location is perfect, within easy walking distance of all major sights and good restaurants, without being buried in the crush of tourists in the old town. All email contact with Nikola was quick and pleasant, and though we never met her the friend who let us into the apartment was also very nice. The apartment is indeed newly renovated and clean, with a well-equipped kitchen.
We did have a water issue (almost no cold water), but it was never unlivable, and Nikola was quick to get a plumber in to fix it. The bed is definitely not memory foam, though. It wasn't particularly uncomfortable, but we were disappointed as the promise of a really comfortable bed for our long-ish stay was part of why we chose this apartment. I would also suggest bringing earplugs if you are a light sleeper. The neighborhood isn't super-loud, but it was too hot for us to sleep with the windows closed and the 4 AM post-drinking pool games next door were annoying! However, this is nothing unusual if you visit a major tourist/party destination city in peak season and chose to live centrally.
Overall, this is a very convenient and reasonably comfortable apartment for a fair price, and we were happy with our choice to stay here.