We were lucky to find such a large and comfortable apartment. We were there for 3 weeks at Christmas and New Years. The apartment has 3 bedrooms (we used 2) with comfortable beds. There were extra pillows and bedding. Plenty of towels and a nice hot shower. We enjoyed the large ceiling to floor windows. For summer visitors there is a blind you can use to keep sun out, but in the winter we enjoyed the light. There is a very nice balcony where we sat for coffee and evening drinks. It was a relief to have supplies when we arrived - cooking spices and coffee as well as dish soap and laundry soap and plenty of toilet paper. All much appreciated. The clothes washer was in the kitchen and nice to have for our extended stay. As long as a vacuum cleaner if you are there for a long time. We ate in every morning and quite a few nights too, and didn't have any serious issues with pots and pans etc. The kitchen is really nice with a large window that opens up. The living and dining room were also used quite a bit and we had no issues. The t.v. is all in Spanish or Catalan, but we didn't mind. The wifi was excellent.
As far as the location goes, it is not right in the centre of Barcelona, but it was easy to take a taxi anywhere. There was a neat bike rental system that you might want to look into before you come though as you need to register. We ended up using the metro after a week. The station we used was about a 10 min walk up the street, and could get almost anywhere within 1/2 hour or less. Easy system to use, buy the card of 10 (or 12) as it is much cheaper.
For groceries there is a corner store right across the street that has everything, even alcohol. We often shopped there but you will have more choice if you walk to the mall where there is a much larger store (10-15 walk) It was excellent. Found a great bakery on the same street as the apt on the way to the metro station.
We could walk to the beach in 5 min? Too cold to swim when we were there but it looked like it might be a nice place in the summer. Also, there was a marina there and a number of restaurants.
We had a great vacation and this apt was a great place to have our base. If you want a bit more space and don't mind public transit, then go for it!