i like them since "10,000 smoothed out slappy hours"
then i listened alot of Kerplunk until Dookie, Insomniac, Nimrod, Warning, International Superhits, Shenanigans,
Short Music for Short People, American Idiot and of course the ever Controversial : 21st Century breakdown,
upon following thru their music for most of my listening life, i say that greenday still sound, feel, and taste the same.. but like any other musicians, (most on PUNK ROCK) they come to maturity and shift their messages from "I don't Care about your life coz i have mine" to world peace and anti-war concepts, greenday is sensible on American Idiot and 21st Century Breakdown, though using smoother music to try to reach masses who are not into punkrock, but what the heck! message is more important
try listening to them and prove to yourself they make more sensible music today compared to their "firsts"