"[6] Byrds expert Tim Conners has called the song "the Platonic ideal of a Byrds song", in reference to the presence of some of the band's early musical trademarks, including Jim McGuinn's jangling 12-string Rickenbacker guitar; Chris Hillman's complex bass work; David Crosby's propulsive rhythm guitar, and the band's complex harmony singing and use of wordless "aaahhhh"s.[7] Band biographer Johnny Rogan has also commented on the song's country-influenced guitar solo.

[6] Music critic Mark Deming has said that, lyrically, "I'll Feel a Whole Lot Better" takes a sardonic view of romance, with Clark undecided about whether to break off a relationship with a woman who hasn't been entirely honest with him.

[8] The song's refrain of "I'll probably feel a whole lot better when you're gone" betrays Clark's uncertainty about ending the relationship and whether such an act would be the answer to his problems or not.

[8][6] Deming has also pointed out that the use of the word "probably" in this refrain is key and lends the track a depth of subtext that was unusual for a pop song in the mid-1960s.

[4] Although it was initially released as the B-side of the "All I Really Want to Do" single, "I'll Feel a Whole Lot Better" was itself heavily promoted by Columbia Records during the time that "All I Really Want to Do" spent on the Billboard charts.