[5] Matthew Thiessen described the album as being different from their other material, stating, "We made it a point to pull back all of our usual tricks in the recording process, and forced ourselves to determine how to present each song in the best and most concise way.

He went on to say that "the band have moved away from just writing energetic pop/punk songs, and instead have written an album that is creative, solid and mature, but at the same time not losing their great songwriting skills.

He called the "resulting" album "a delectable batch of experimental modern pop that may surprise longtime listeners, but will surely have them joining the veterans for the positivity-laden party.

"[29] Jesus Freak Hideout's Roger Gelwicks commented that "at the very least, Collapsible Lung is a daring collection and will retain a sundry of reputations", and stated that the album is a welcome "experiment that keeps the band's fans on their toes, doing more right than wrong in the process.

"[25] In addition, Cortney Warner of Jesus Freak Hideout wrote that "Collapsible Lung continues to solidify the confusion" because it is "almost too inconsistent, and at times it can feel more like a B-side album rather than a collective LP.

[28] At Alternative Press, Scott Heisel felt that "now we're left with Collapsible Lung, the dreadfully plastic yang to Forget's emotional, powerful yin.

"[19] Randall Colburn of Consequence of Sound wrote that the album is "frontloaded with generic dance-pop tracks", and evoked that the release is "weighted down by a parade of faceless women, many of whom are reduced to mere sexual objects, resulting in a record that reeks of adolescent rebellion at best and pandering at worst.

"[23] CM Addict's Kevin Thorson said that the album's "inconsistencies and poor lyrics are things you would expect from possibly a debut artist not from seasoned veterans", and because of this wrote that "Relient K can do much better.