After Lennon's death in 1980, the song was considered as the third Beatles reunion single for their 1995–1996 retrospective project 'The Beatles Anthology', following "Free as a Bird" and "Real Love", both based on Lennon's demos. Instead, it was shelved for nearly three decades. It was later completed by the surviving bandmates Paul McCartney and Ringo Starr, with overdubs...and included guitar tracks by George Harrison from the abandoned 1995 sessions.

FANTASTIC video though.

I scribbled this response on my facebook

I grew up with The Beatles. Not literally, but they were the backdrop to everything for the first ten years of my life.
The new track 'Now And Then' is not the best Beatles songs ever; possibly because it was really John Lennon solo which was found and recorded by the remaining members of the band several years later, which is nothing new in Rock'n'Roll, so it became a Beatles track.
AI has made it more possible, and it is produced by Giles Martin the son of the main Beatles producer George Martin.
I did say it's not the best Beatles song, BUT, it is still a good addition to their repertoire. Not a bad song at all, and when complemented by the excellent new music video it becomes a masterpiece.
Meaningless to those who don't remember The Fab Four, or those who are determined not to like them or it, but to the majority of true music fans this is a monumental moment in musical history.

I think it's rather tuneless but enjoyed Peter Jackson's film of the song.