My wife and I stayed for a week in Sixtine's flat. It was a great location with lots of activity in the local streets, parks, and up the hill at the churck ... nice views of the Eiffel Tower at night. The place had everything we needed and there are lots of local restaurants and shops all within a few minutes walk.
We had always stayed closer to the centre of the city but our original booking cancelled at the last minute ... so we took a chance and ended up getting a larger and much better equipped place for about $750 less for the week.

It was a bit tougher coming back up the hill - but we tended to walk at least one way (if not both ways) every day as we made our way to the Louvre, Orsay, Picasso and other museums - bring comfortable shoes and you will see a lot of neighborhoods up close.