debut album, titled the xx. They exemplify indie-rock with an atmospheric, dance beat bent - there are no extraneous notes to be found on the albums. The beauty of the xx is that you can listen to them repeatedly and find different songs to like each time, and you can play them as background music or listen attentively. Basically, they're all-purpose listening.
One quality that sets the xx apart are the vocals. The vocal duties alternate between two members, Romy Madley Croft and Oliver Sim. Sometimes the two alternate on the same track with clever calls and answers. Neither is a perfect singer, but both have a haunting quality to their voice.
The xx are also masters of the electronic crescendo (listen to Reunion, from Coexist). I can't think of another band of the top of my head that is this skillful at creating tension in songs that are so stark (if you can think of another band, let me know in the comments).
I would encourage you to listen to either disc, and eagerly await their next.