Spacious and beautifully furnished in an eclectic taste. It is semi open plan but private enough for two couples and certainly a couple and older children. There is an ensuite bathroom and a separate toilet in the hallway.
The kitchen is superb - there is a Nespresso machine- and there are plenty of vessels and utensils to cook properly.
The main bed is really comfortable. Adjacent is an incredible en suite bathroom with a big bath and huge rainforest shower.
The second bedroom has 2 single beds that could be a double.
It is down some stairs. Not exactly a basement as it gas massive windows overlooking a private square but for those less mobile or small children it might be a bit more difficult.
It is between Montmartre and Pigalle and close to the metro (3 minutes walk) and you can get to e.g. Le Louvre in about 20 minutes so really easy. Walking to Notre Dame is about 50 minutes and is a pleasant and interesting stroll. To Sacre Cour is 5 minutes walk also to the Square if Montmartre so you can't be in a better location really. But once you are inside it is really quiet too! You would not know there was a buzzing environment outside your front door.
Wifi is excellent, constant hot water, private, great location.... I doubt there is anywhere better!