We booked the apartment based on the balcony and it was definitely the highlight - such a lovely place to sit and eat breakfast or have a drink in the evening... and you can even see the Eiffel Tower in the distance!
The location is great too, really close to Nation Metro stop and some nice cafes. Walking distance to Bastille which has a lovely market and restaurants.
I knocked a star off because the apartment was dusty and we had to make our own bed. But overall we really enjoyed our stay and loved Paris.