Yvonne place is in an excellent location. Dora greeted us on arrival and was available at the time we had agreed. Many great places for breakfast, dinner and easy access to transportation nearby. There is also convenience stores around and small markets.
It is a great place for 3 (I think 4 would be tight) Bathroom is bigger than most Barcelona apartments, but still small as compared to other places. There are some renovations that are undergoing in the building where the flat is, so if you want to wake up later in the day this might be somewhat difficult during this time.
Regardless, I would definitively book again given the great location it is in and the great hosts involved in taking care of the place.