It's a bit hard to judge it on its own merits, as a 'new' Beatles song is such a big deal.
No, it's probably not as good as the best things they ever did, and yes the production is a bit syrupy, and No, George didn't like it, but for me, a 1978 song by John Lennon that was on a tape labelled 'For Paul' that contains the lyrics 'If I make it through, it's all because of you' with Paul, George and Ringo playing on it is a really beautiful thing to hear.
A nice postscript I think.