We enjoyed the stay in the apartment. The location is great, just several minutes' walk from the metro station and from the beach. There was some street noise when we left windows open at the night, but you can always use air conditioning.
All our questions were answered promptly before and during the stay. Sweet Inn offers the possibility to store luggage at their office in the Barcelona center which is great in case you arrive early or leave later in the afternoon.
We have found the apartment children-friendly, there is youtube on the TV, Wi-Fi, and Olympic decorations. Also, there was a welcome pack with Nespresso capsules, tea, and sugar in the kitchen. Appartement offers enough space to store clothes and a big fridge in the kitchen. Furniture had been clearly used for some time (almost a perk if you have kids), however, all was functional.
Just note that to complete the reservation process there is an external form to be filled out, a city tourist tax and a safety deposit to be collected. Also to use smart lock you need a special app.
Highly recommended, we enjoyed the stay