Fantastic film, with a distinctive look, style, and tone that both reflected and influenced the late 60s just superbly.
The Eleanor Rigby sequence is probably my favourite part from an aesthetic point of view, but there are loads of things to enjoy throughout. The pacing is occasionally a little off, feeling as it does rather episodic at times (not unlike Disney's Alice in Wonderland), but it always links back to a song and so everything works out just fine. The film does peter out a little right at the very end, and the apparent grand finale (before the live action section) isn't as memorable as it could have been. But given that production was completed in record time - not much more than a year from go-ahead to premiere - it's hard to see how it could have been much better.
Probably Britain's finest contribution to the world of animation, in my humble opinion.