Location! Location! Location! The view if Notre Dame made me happy every time I looked out my window.
It was easy to get wherever you wanted to go. I didn't cook, but everything was there if you wanted to prepare a meal.
The linens and towels were soft and of good quality. The flat was nice and clean.
As others have warned, the stairwell is narrow and the lift small. You need to walk up about 15 stairs to get to the lift and there are another 7-10 steps down/up to the flat. So as long as you don't have large luggage or have a problem with stairs, you'll be fine.