Mary J. Blige performs ‘Stay With Me’ with Sam Smith at Grammys...

I'm not a fan of Sam Smith. This song has become such a hit I've heard it pretty much everywhere. Doing indoor grocery shopping at Asda or enjoying a quiet morning coffee at MacDonalds is not happening without that song playing in the background.
This is how I know the song well enough to observe it's better sung with JUST the original singer. Not to say Mary's vocals were bad. They were just okay for what they were. The track can be found on Sam's Grammy-winning album 'In the Lonely Hour,' which dropped in stores last May.

Thoughts?