Our group of four adults stayed there at the end of August. We had an overall great experience: the check in was easy and they stored our luggage until we could access the apartment, the rooms were spacious and provided enough separation for two couples to have privacy, the kitchen was well equipped and every area was very clean.
The Sagrada Familia is literally a couple blocks aways. This location is close to three different subway lines so it makes sightseeing quite simple. We also found that commuting by taxi was easy and efficient for four adults; it cost about €7.50 per ride to reach any major sightseeing.
There is a convenience store close by that is well equipped - we even got umbrellas here for a rainy day. We got fresh baked goods, produce and meats at local stores every day; everyone was super friendly.
If you want to commute easily around Barcelona, stay in a nice area that is not noisy or overrun by tourists; this is a great place. For us going to the beach was a half day trip, if you want to spend more time in Barceloneta or any surrounding beaches, I would probably recommend staying closer to it.