New Beatles song features John Lennon's voice

A new Beatles song produced with a little help from artificial intelligence and including the vocals of John Lennon was released on Thursday -- to lukewarm reviews.

The song comes more than four decades after it was originally recorded as a demo, but despite the hype left critics distinctly underwhelmed.

"´Now and Then´ is not terrible... But ultimately, it´s kind of mundane," wrote Geoff Edgers in the Washington Post.

The Times daily in the UK said the song showed AI being used to its best advantage.

Parts of it also conjured up "that classic, bittersweet, Beatles-esque flavour", wrote reviewer Will Hodgkinson.

"Unfortunately, none of this can mask the fact that the Last Beatles Song is far from a lost masterpiece," he added.

"´Now and Then´ is wispy, indistinct and, frankly, a bit of a wet ballad. It sounds more like late-period Lennon than any moment in the Beatles´ career."

Variety magazine took issue with the lyrics in particular.

"It´s hard to imagine Lennon being happy with lines like, ´I know it´s true, it´s all because of you/ And if I make it through, it´s all because of you´," wrote the magazine´s Jem Aswad.

He said the song sounded more like a "rough and incomplete sketch of a song reassembled and elaborately embellished, rather than a complete one".