The episode guest stars Gwyneth Paltrow as Holly Holliday, a substitute teacher who takes the place of glee club director Will Schuester (Matthew Morrison) while he is ill. Cheerleading coach Sue Sylvester (Jane Lynch) causes problems as the fill-in substitute principal of William McKinley High School after she gets Principal Figgins (Iqbal Theba) infected with the flu, and glee club members Mercedes Jones (Amber Riley) and Kurt Hummel (Chris Colfer) experience tension in their friendship.

The actress felt that Will's illness allowed viewers to see the couple with their defences down for the first time, and that the addition of Holly highlighted a double standard in their relationship.

[3] All of the songs performed, with the exception of "Conjunction Junction", were released as singles, available for download,[19] and "Forget You" is featured on the soundtrack album Glee: The Music, Volume 4.

[31] Viewership declined from "Never Been Kissed", which was watched by 1.08 million viewers; despite this, the series registered a rise from eighth and twenty-seventh in the daily and weekly program rankings respectively.

[39] Brett Berk of Vanity Fair criticized the focus it placed on the adult characters at the expense of the teenagers and the disregard for continuing plot strands in favor of a celebrity cameo, but concluded that "despite all that, some of it kind of worked.

"[40] The National Alliance on Mental Illness (NAMI) took exception to this episode, which, it stated, "mocked and trivialized bipolar disorder" during Paltrow's history classroom scene, in which she role-plays as Mary Todd Lincoln.

Online's Kristin dos Santos called it Emmy-worthy, with the former rating it amongst her best ever performances,[37] and the latter stating that Holly received "some of Glee's best-ever one-liners.

[45] Canning stated that Paltrow's casting could have been distracting, but instead she fit the role "seamlessly",[35] and CNN's Lisa Respers France compared her performance favorably to Britney Spears's cameo in the episode "Britney/Brittany".

Berk found her "surprisingly great",[40] and Poniewozik said that while her casting was somewhat distracting, she was able to make Holly a sympathetic character without overdoing her neediness and commitment-phobia.

[39] Jen Chaney of The Washington Post recommended a "lengthy moratorium" on internet criticism of Paltrow, suggesting that with her Glee appearance, her "mission to charm the American public may be complete".

[36][39] In contrast, VanDerWerff criticized the sub-plot for ignoring Will's culpability in the breakdown of his marriage, and expressed displeasure at his inconsistent characterization, deeming it one of the season's biggest problems.

Fallon took offence at Glee's sole overweight black character turning into a "fried potato-addicted junkie",[45] and both Berk and Stack commented that while they had hoped for Mercedes to receive a major storyline, they did not want it to be centered on her weight issues.

[37][40] Semigran called it "rather disposable" but appreciated the "silliness and levity" it introduced,[36] and Respers France noted that she did not mind the storyline itself, but disliked Kurt lecturing his supposed best friend.

Anthony Benigno of the Daily News gave "Conjunction Junction" a grade of "A"; he noted that ordinarily he would have declined to review it due to its short length, but said "what a glorious ten seconds it is".

[48] Benigno and Poniewozik criticized the sanitization of "Forget You", but while the latter found it inferior to the original version, the former preferred Paltrow's deeper voice and graded the song "A".

[39][48] Rolling Stone's Erica Futterman felt the censorship of the song did not adversely affect its success, and deemed Paltrow's rendition "charming and sassy".

[49] Megan Vick of Billboard called it "the most exciting number" of the episode,[50] and Stack went further in his praise: he bestowed a grade of "A+" and lauded it as "one of the most memorable and energetic Glee performances ever, thanks in no small part to Paltrow".

[37][48] Futterman called the recreation an "impressive feat", but likened it to hallucinatory Britney Spears covers in the episode "Britney/Brittany" in that it "stands alone better than it fits into the plot.

"[49] Vick was critical of the performance, observing that Glee covers from musicals often introduce classic songs to viewers with a modern twist, an element which was absent in "Make 'Em Laugh".

[50] The Chicago cover also left some critics wanting, and Futterman, The Wall Street Journal's Raymund Flandez and The Atlantic's Patrick Burns all found its choreography lacking.

Benigno graded it "B", though he said that by using "Singin' in the Rain" as the chorus, the song lacked catharsis,[48] a sentiment echoed by Flandez, who praised the costumes, props and staging, but wished the rendition had had more "bite" and "attitude".

She deemed the staging implausible, questioning how a glee club in financial difficulty could afford elaborate water features for a rehearsal number.

[37] Amy Reiter of the Los Angeles Times appreciated the choreography and the manner in which "Paltrow's sassiness undercuts [Morrison's] overripe sweetness", and named it potentially her favorite group number of the season.