We really enjoyed staying in this apartment for a week with our baby and two young children. The place is well set up for little kids, with a cot, high chair and baby bath. Marina very thoughtfully lent us some books and toys.
Things we particularly liked about the location- the library next door has a huge children's section that includes some foreign language books, and it is close enough to Park Guell that you can go there before 8:30am to see the monuments, when it is free and fairly quiet.
The apartment was very clean, new and nicely decorated. It was easy to get around using the metro or bus. We would gladly stay here again!