This is a comfortable, very well located apartment to stay in Paris! I enjoyed my time at Anne's flat very much and the location is excellent. The street is fairly quiet and there are two metro stations within 5 minute walk. As a single traveller, I felt very at ease and safe at the flat. I had a little trouble with locking the door as the bottom lock was broken during my stay, but overall it wasn't a problem. The stairs are a good workout and perfect for staying healthy during your vacation! As long as you are healthy and fit, going up to the 5th floor shouldn't be an issue!
Anne had a very nice housekeeper who helped check me in and out and communication with Anne during my stay was easy.
I enjoyed the neighborhood very much and there are great boutiques and cafés nearby. I recommend foundation cafe for coffee, nanashi for simple, delicious meals and OFR for special books and hard to find magazines.
If you want a nice place to stay in the center of Paris, this is a great flat to consider!