If you're not familiar with Pentatonix, they are a five-piece a capella (meaning they sing unaccompanied) band from America. They sing pop songs and pop versions of Christmas songs - look them upon youtube. Normally I'm not much of a fan of classical songs being sung in a pop style, but I love the Pentatonix Christmas albums; the same songs tend to be played ad nauseum every December, so it's nice to throw something a little bit different into the mix. Pentatonix have some beautiful arrangements and obviously put a lot of work into the harmonies. It's not perfect - not every song is a stand-alone classic and to be honest I felt the playing time was a little short and they could easily have added another couple of songs. But I would have bought this for Carol of the Bells alone.