When a voice has the stopping power to make the listener stop everything he/she is doing and pay attention to what is being heard, it is worthy of praise. Woodkid's inflections are mood-inducing and the lyrics thought-provoking. The collaboration for the Insurgent Original Motion Picture Soundtrack is a highlight for its dramatic cinematic effects.
I dare you to play this one in a volume that is not loud. Lykke Li is a pleasant companion and adds to the emotiveness overall but it is the main artist's stripped vocal on the bridge that kills us and makes the promise of never letting you down that much empathic.
While it was a lifelong dream for Woodkid to sing a duet with Lykke Li, I believe this is as much as a win for her as it is for him. Scratch that, we won with this one.