Short summary: we generally enjoyed our stay in a really nice, comfortable and spacious apartment which was exactly as on the pictures. It is very well located right off plaza Catalunya, yet it is not noisy in terms of street noise.
However, we had to contact their offices much more often than we wanted and the customer service performance was poor. And you might find yourself poorly served in case you need help. One nice lady on the third day was able to finally fix our key (literally) issue. It is also not ideal that you need to pick the key up and nobody hands over the apartment.