I would give Rosa & Nicolas and the apartment the highest possible rating. We absolutely loved Rosa y Nicolas's place. It was great for family due to easy access to metros and walking distance to much of what Barcelona offers.
The apartment itself is very nice and modern. Wifi worked great. The bedrooms are nicely spaced out. The apartment is close to several parks, which our children appreciated. There is a really terrific pizza place/Italian food just up Enteca called Vesuvius.
Rosa y Nicolas are great, great hosts. They let us check in early and check out late. They gave us great advice on the city. They even had little gifts and a Christmas tree because they knew we were here for Christmas with our children.
We hope to see you again!