The slight echo on Paul's voice, and the sheer excitement of that shouted 'Four!' advises you of the following -
you are about to hear a three-minute template for the thrill of the musical revolution that is going to change your world for ever, complete with a jumping bass line (decades ahead of its time) and the euphoria of John and Paul whooping into George's solo, and Ringo's ringing fill bringing them all out again, before that final clanging chord that demands that you play it all over again.
It is rock and roll perfection, and I would die happy if I had written just that, and nothing else.