We had a great stay and would definitely use this place again when returning to Barcelona. I would do recommend this place overall.
It's well placed - about 10 minutes walk from Placa Catalunya and the Gothic Cathedral and about 25 minutes from Sagrada Famiglia. The space worked really well for us with a main one-bedroom flat with a huge, airy sitting room and covered terrace and a linked studio flat. There is a lift up to the flats which helps with luggage. The flat is in need of a few minor repairs but nothing that affected our stay.
Things that could affect whether it's suitable for you: the bedroom in the main flat is really small and the shower room and the loo are not en suite, the studio flat has steps up to the kitchen and down to the living area so not suitable for anyone with mobility issues, the kitchens are fine but not equipped for lots of cooking (not a problem for us as we ate out) and the check in process is very friendly but you do have to go to the hotel (which was about half an hour in a cab from the airport or 20 minutes via metro from the train station) and then use the free cab they provide so factor that into your travel plans.