Featuring a variety of songs and sketches about his day-to-day life indoors, it depicts Burnham's deteriorating mental health, explores themes of performativity and his relationship to the internet and the audience it helped him reach, and addresses topics such as climate change and social movements.

In "All Eyes On Me", Burnham sings for a pre-recorded track of an audience: he reveals that he stepped away from live comedy five years prior because he was suffering panic attacks onstage; his mental health had improved enough by January 2020 for him to consider returning before "the funniest thing happened".

A flashback introduces the song "Goodbye", wherein a younger and older Burnham both resign to their isolation, incorporating melodies and motifs from throughout the special.

After the song, he finally leaves the room in a white outfit, only to be locked out as an unseen audience applauds and then laughs at him for attempting to get back inside.

[35] Brian Logan of The Guardian reviewed that though some outtakes were only for fans of Inside, "some of the material sparkles as brightly as the best of the original", including the podcast, "Five Years" and "Chicken".

[40] The Big Issue's Evie Breese, though less fond of "Chicken", praised the songs in the outtakes for their "mental claustrophobia", which continues to be relevant after the end of lockdowns.

[46] Tom Power of TechRadar wrote that it was a "comedy-drama" and its alternation between stand-up material, music and "fly-on-the-wall" scenes makes it feel like the combination of "a documentary and stage act".

[9][44] Eric Kohn of IndieWire identified "weird tonal shifts and abrupt transitions" between different sections of the special,[51] and VanArendonk described Burnham as displaying "performance energy across a wide spectrum of affects and moods".

[48] Power suggested that the setting of a single room is representative of Burnham's mind, explaining that "scattered instruments, clothes and recording equipment signify the cluttered, messy and overwhelming thoughts he has to deal with on a daily basis".

[47] On a related note, Jason Zinoman said in The New York Times that the title has a double meaning, referring to Burnham being inside a single room, and "also his head".

[52] Karl Quinn of The Sydney Morning Herald wrote that Inside employs the limited setting "as a canvas for creativity", but the overall feeling is "claustrophobia and cloying ennui", and even "full-blown depression".

[54] Isobel Lewis of The Independent said that Inside is "largely about comedy itself" and explores Burnham's "complex relationship with his audience", similar to Hannah Gadsby in their stand-up set Nanette (2017).

[9] On this topic, Kohn described that Burnham's "maniacal, passive-aggressive screen presence suggests he's grown cynical about creating art in a world that reduces it to pure capitalist product".

This follows on from Make Happy (2016), in which the closing stage song "Can't Handle This (Kanye Rant)" reflected his ambivalent relationship with his audience.

[48] Through the final scene, in which Burnham watches a recording of himself locked outside while still in the room, Zinoman saw Inside as "encouraging skepticism of the performativity" of "realism".

[45] Rebecca Reid of The Daily Telegraph saw Burnham as not "demonising" or "evangelising" about the internet, and instead "capturing the silliness, the horrors, the brilliance and the total futility".

The majority of the song is "a satirical tune about all the shallow and clout-chasing images that pop up on basic white women's Instagram accounts", according to Bojalad.

[45][60] Reid saw this as a reflection of a young person's life on social media: "Vapid, inane rubbish ... interspersed with occasional moments of boundary-breaking honesty and observation.

She compared Inside with Burnham's earliest YouTube videos and found many similarities in performance style; however, he made "blatantly unfunny, homophobic, and misogynistic jokes" in his early career.

Burnham initially uses his young age as an excuse, but then apologizes for doing so in the next verse: Sanchez argued that the message is that "the first step to being a better person is acknowledging mistakes".

The website's consensus reads: "A claustrophobic masterclass in comedy and introspection, Inside is a beautifully bleak, hilariously hopeful special from Bo Burnham.

[44] Dominic Maxwell of The Times called it "the first comic masterpiece" from the era and Bojalad thought that it could be "a definitive bit of Western popular art to come out" from it.

[9] Kevin Fallon of The Daily Beast had not enjoyed other media made or set during the pandemic, but found Inside "the perfect punctuation on the grand quarantine TV experiment".

Club's Allison Shoemaker described it as one of a small number of works that are an "effective and accurately surreal encapsulation" of pandemic life, and Power reviewed it as "culturally relevant and thematically resonant".

[45] Rachel Syme of The New Yorker viewed it as portraying specifically the "unmoored, wired, euphoric, listless" experience of being online during the pandemic with "a frenzied and dextrous clarity".

[45][48] Fallon said that Burnham's "chameleonic abilities" make the special work, while Shoemaker reviewed the filmmaking as "inherently and marvelously theatrical" and the performance as vulnerable.

[52] Power summarized that the angle and scope of shots, the editing and scene transitions, and the lighting effects combine to evoke "a fever dream".

[51] Both Kohn and Shoemaker compared Inside favorably to Eighth Grade, with Kohn saying that it was "a happy medium between the silly-strange nature of his stage presence and the advanced storytelling instincts evident from Eighth Grade", and Shoemaker opining that it combined "the remarkable filmmaking skill" of the movie with "his usual sharply comedic pop tunes".

[51][54] Zinoman praised Burnham for showcasing a wider variety of musical styles than his previous specials, including bebop, synth-pop and show tunes, as well as becoming "as meticulous and creative with his visual vocabulary as his language".

Bojalad found a verse in "White Woman's Instagram" about the character's mother dying to be the "most remarkable moment of human kindness and empathy" of Inside, experiencing it as an unexpected scene that had stayed with him since his viewing.