The great: Cleaniness, light, space, amenities. It's a gorgeous flat with the benefit of an elevator.
The not-so-great: It's a little outside the main tourist areas, but it's quieter and next to a nice park. Wifi connection was very spotty.
The ugly: Customer service for said wifi connection issue was incredibly irresponsible. While I definitely appreciate the minor refund after we got back as an acknowledgement of the issue, the way this was handled significantly affected our stay in Barcelona :(