We arrived in Barcelona with our 9 month old daughter. We stayed here at this location and first off, the apartment is MUCH LARGER than the pictures!! we were so surprised by that. That was a huge plus.
It was so spacious and that was pleasant because it was good for the three of us. We rented the 5th floor location, you have to walk up a flight, take elevator,walk down a flight, but we were aware of this before hand!

Pros:
The apartment is extremely clean, and there was coffee pods and water in the fridge. There is a washing machine, drying rack and iron too. Came in handy when we washed clothes there. the second bedroom has a little tiny balcony that opens to the street. You can see the temple del Sagrat Cor from the window =)
Air conditioning was great, and they also gave us a high chair to use for our baby.
THEY ARE EXCELLENT with customer service. they responded very fast and that is a huge plus, no waiting.
They waited for us at the apartment due to delays at the airport, that was so nice. Gave us maps of the city and recommendations of using the metro.

The area is good, going to the left of the apartment you will find great restaurants, some that are well known in the area as well. Best coffee is to the right at Federal Cafe.
The metro is a 7-10 min walk and it goes everywhere. We actually walked a lot and rarely used the metro, so it takes 30 minutes to walk from central areas of Barcelona, not bad a all as you can see the whole city. We used taxi a lot as with an infant to get to further places, it is hard to hail a taxi in that area, you have to walk to main roads.

Kitchen is fully stocked with utensils, pans and pots, napkins, etc. etc.
Towels are great and large.

Cons... not really cons as we weren't hugely bothered by it:
Air conditioning is only in one room- the living room. So we put the crib in the second bedroom and had to turn the fan on and leave the door opened so it wouldn't overheat as we were visiting in July- very hot month.

there is a weird, strong smell that comes from the bathroom window if left open, so we closed it but then no ventilation. Shower curtain dirty. also the hot water in the shower does run out, which made us have to take shorter showers, but not a big deal.

Overall, this was such a pleasant location, take the metro into town or take a long stroll, both are great. If with child it would be easier to stay more centralized due to their napping schedule, but we ending up using the taxi... but we made it work. Beautiful home and the most FRIENDLY hosts!!!!!! highly recommend !!!!!!!!!