We stayed 5 nights and had a great time in Barcelona. The location of the apartment is great, right near the beach. So you can combine exploring the city with some beach time.
However, the apartment is in an older part of town in an old building so lacks some comfort. For example: smelly bathroom and the mattress is not flat so both people keep rolling towards the middle and wake each other.
If you are ok with that, then it's a great place to stay because of it's location.
Also, the check in was done by a lovely lady which was very nice.