The album proved to be a success, receiving acclaim from both critics and fans, as well as selling over five million copies.

In mid-2004, the band took a break from touring and filmed a documentary for War Child Canada in the Democratic Republic of the Congo.

"Two UN people arrived at the scene and gave a speech about how everything would be fine," bassist Jason "Cone" McCaslin mentioned.

Vocalist/rhythm guitarist Deryck Whibley mentioned that he thought that a day after the UN gave an update about safety, he was expecting they would be able to evacuate.

"We went to the hotel's restaurant to get some breakfast, when the gunfire just got closer to us," said lead guitarist Dave "Brownsound" Baksh.

A U.N. peacekeeper named Charles "Chuck" Pelletier instructed the residents of the hotel to leave the restaurant.

"We put more elements in this time around, and it feels like the next logical step in what we want our band to sound like".

They were assisted by Pete Martinez (at Sound City), Miles Wilson (at Sound City), Jason Cupp (at Ocean), Chris Stringer (at Reaction), Robert Poteraj (at Soundtrack), Matthew Davies (at Soundtrack), and Steve Sisco (at Sidecar).

"Intro", "Angels with Dirty Faces", "Open Your Eyes", "Slipping Away", "I'm Not the One", "Welcome to Hell", "Pieces", and "88" were mixed by Andy Wallace at Soundtrack, with assistance from Sisco; John O'Mahoney operated Pro Tools.

"No Reason", "We're All to Blame", "Some Say", "The Bitter End", and "There's No Solution" was mixed by Tom Lord-Alge at South Beach Studios in Miami, Florida with assistant engineer Femio Hernández.

Specifically, "The Bitter End" is thrash metal and "Welcome to Hell" is hardcore punk,[5] while the fifth and eleventh tracks, "Some Say" and "Pieces" respectively, are alternative rock songs.

[6] Michael Endelman of Entertainment Weekly described it as "a meeting of two worlds — extreme metal and pop-savvy punk — that rarely pass each other in the halls, let alone hang out after school.

"[15] Dave Simpson at The Guardian stated "The spiky quartet furnish their usual shouty vocals with grinding riffola and twiddly guitar solos, just as the rest of the post-Linkin Park world are realizing nu metal wasn't such a good idea.

"[6] PopMatters writer Ethan Stewart described the album's sound as "primarily defined by a merger of heavily Metallica-indebted thrash with the kinds of alternative metal closest to System of a Down or Breaking Benjamin depending on the song... [it] is also structurally reminiscent of the melodic hardcore albums from the same period, namely No Warning’s Suffer, Survive and Rise Against's Siren Song of the Counter Culture.

Common Sense Media gave it four stars out of five, saying "Rugged intensity makes up for the diminished playfulness.

You might not be able to do much about it, but perhaps – following the example of Sum 41 – you can write some interesting, lyrical songs about the stuff that drives you crazy", and also called it "socially conscious punk rock".

But the band still rocks hard 95% of the time and the fact they've gotten heavier actually accentuates their poppyness better than the punk aspect.

Stuart Green of exclaim.ca said "Musically the band has never sounded more determined or cohesive (the notable exceptions being the Oasis sound-alike "Some Say" and the power mellower "Slipping Away" and "Pieces").

Diamond in the Rock said "Although some hail Chuck as a complete departure from the band's enjoyable punk style, this album adds diversity to Sum 41's discography as the hardcore rock vibes lend to an engaging, albeit satisfactorily brief, sound."

The highlight of Sum 41's discography is going to come when they fully embrace their metal influences and make a straight-up metal album, and sadly Chuck misses the mark", but also added "If you are still under the impression that Sum 41 is a joke band or a Beastie Boys-wannabe, give some of these songs a try, and you may be pleasantly surprised."