Sylvie's apartment was absolutely lovely. We were in Paris for 3 weeks, including some of very warm days (over 30C) and after France won their semi-final game in the World Cup. Which is really just to say that we didn't melt and the windows are impressive at blocking out sound when we needed them too. The small elevator in the building (fits about 2 people) was a lifesaver and the building was very secure. Although we never did feel unsafe in the area; there is pretty great foot traffic - not too crowded but not too deserted.
Washing machine and dishwasher were all easy to use.; everything you need is in the kitchen if you want to cook your own dinner, or just reheat takeout. TV and internet worked great. And there are a bunch of great restaurants even in the immediate area (and boulangeries!).
A few things of note. Sound really travels up the buildings if you do have the windows open so things can get a bit loud, including the window in the bedroom overlooking the inner courtyard area; activity outside doesn't really die down until sometime between midnight and 2am. The microwave/oven combo is a bit trickier (most of the instructions are in French), but it wasn't too difficult - just takes a bit more concentration. These weren't an issue for us because we're in Paris and the outside noise was just part of the charm.