I'm not going to comment either way on the "spin off" aspect and/or whether Lennon would have been proud or angry.
The song as it stands is a good one. very well mixed, great vocals. the piano is a tad muddy at the intro, then clears up immediately just before the vocals come in (when the bird chirps are gone and the video shows the artist at the piano). of course the piano sound at the intro is very similar to the recording of the song this was derived from, so maybe that was on purpose. I think if that's the case I would have cleared the piano up at the exact same moment the vocals came in, not before.
I like it - very nice work!