We stayed in Lucy's place for 9 days, and had a great time. The flat's location is great -- lots and lots of great food within a few steps, right next to beautiful Montjuic, and well-served by bus/metro lines -- and the flat itself is bright and well-equipped. We especially liked being able to have a cup of coffee on the terrace! The flat is just as described; it's not large by US standards (welcome to Europe!) but is well laid-out and comfortable. El Poblesec is a wonderful neighborhood that's laid-back and friendly without the tourist crush of the old city.
Communication with Lucy was fantastic -- we had terrible flight delays and cancellations getting to Barcelona, and she was flexible and quick to respond at all times. It made a stressful situation much less stressful.
In short: we'd stay here again in a heartbeat!