The most significant thing I noticed when I listened to Please Please Me a couple days ago is in "There's a Place." For most of the song, John Lennon and Paul McCartney are singing in harmony, but McCartney drops out so that only Lennon sings the line "When I'm alone." That this line lacks a harmony part (unlike the others surrounding it) illustrates that being "alone."
Similarly, the line "Like, 'I love only you'" is sung only by Lennon (with McCartney and George Harrison singing "ah"s behind it), and there's a connection between this single voice and the exclusivity of "only you" in the line.
