Two of Us was still called On Our Way Home when it was recorded which, though it may not be a better title, is in a more prominent place melody-wise. The song seems like a return to the early Beatles style with dual-lead vocal and all acoustic guitars. There's a 3 note guitar intro that's very hooky (Ticket 3) coupled with a false ending (Ticket 47) and even a whistling coda. The song motors along nicely, though it does slow down over the duration.
McCartney demonstrate his trademark lyrical vagueness in this song. Are the 'two of us' Lennon and McCartney or Paul and Linda? Most likely a mutated combination of both.
Technically the lyrics run the gamut of good, bad and ugly. The internal rhyme of hard earned pay/on our way back home is clever and moves the song along. The mildly nonsensical sending postcards / writing letters on my wall could be a play on words (letters of the alphabet vs written epistles) but two of us...standing solo? And just like The Long And Winding Road, Paul sets up a rhyme scheme only to abandon it when the going gets tough.
sun-way/paper-nowhere (with bonus 'nearly rhyme' raincoats-solo)
The real songwriting gold though, is in the odd time changes coupled with the melodic cells and we'll look at those next time.