[1][2] Beatles biographer John Blaney sees this as continuing the theme of the album, as Lennon strips away another layer of myth that hides the true reality.

[2] Mellers points out that the song's mood of isolation is intensified by the "bare, open fifths" played by the piano and by the silences incorporated into the sad melody.

[4] Recorded at EMI Studios on 6 October 1970, Lennon double-tracked his vocals for the middle section, which were panned to each side in stereo.

[4] Ben Urish and Ken Bielen describe "Isolation" as "direct and moving" and praise Lennon's vocal as being both "animated and nuanced.

[1] Stereogum contributors Timothy and Elizabeth Bracy rated it as Lennon's 6th best solo song, saying that it seems "to wearily recognize absolute loneliness as an inevitable condition of the human experience" and features a "beautiful, ascending piano line reminiscent of nothing so much as Duke Ellington's breathtaking standard 'In a Sentimental Mood'.

While he eventually finds his bliss with Yoko, Lennon empathises with those who feel alone in the world, sounding world-weary as he delivers the main chorus line.