 Musically , 21st Century Breakdown is similar to the punk rock style of American Idiot , but many critics have claimed that Green Day 's traditional sound has evolved in the five years since their last release to incorporate new influences such as heavier , louder pop rock and stadium rock on an epic scale . Rob Sheffield of Rolling Stone indicated that the album sports ballads that are Green Day 's most polished ; he claimed that the band " combine punk thrash with their newfound love of classic @-@ rock grandiosity " . MTV compared the material to that of classic rockers like The Who , while Spin called the title track " Green Day 's most epic song yet " . Cool has remarked : " It 's important to us that we 're still looked at as a punk band . It was our religion , our higher education " . However , he also noted that Armstrong had delved into the past in writing 21st Century Breakdown , gleaning inspiration from the artists who shaped rock music . Armstrong himself has stated : " Ground zero for me is still punk rock . I like painting an ugly picture . I get something uplifting out of singing some of the most horrifying shit you can sing about . It 's just my DNA . " 
