Its sounds like there was some studio magic going on here (reverb and such) but I cant think of anything else he has ever done that has been as strong vocally as this. The beginning "oh my love" is just unexplainable and almost unhuman.
IMO around this era he was consistently pulling off some of the greatest vocal performances of his career, even the B-Sides contain some astonishing stuff.
I think Room At The Heartbreak Hotel holds it own against Unchained Melody.
I still think that Bono sings too bombastic in that version. Their version of Unchained Melody sounds quite clumsy, IMO. I prefer the cover by the Righteous Brothers.