This version by Pentatonix brought some extra dimension into Bieber's music style. I actually like it way more than the original purely pop piece by Justin. No secret that Pentatonix focus on the vocal line most of all, but in this case the piano melody also matters. It's slightly deviating from the standard one and the rhythms are fuller and richer here. All in all, it's a bit challenging to play at start but then you just catch the flow. Big pleasure!