Greenday's been a band for 16 years by now, scoring their first big hit about 10 years ago with "Basketcase". So I don't think they rate as a "new" band at all. Just think about Queen after the Magic Tour (time of existance of the band). I'm not comparing the two bands' music or quality or anything. I'm just saying that Greenday is not not a new band at all.
I got into them around 1997 when a friend of mine lent me their Nimrod CD (the one with "Time of your life" in it) and I thought it was pretty good and well produced for a punk band. Their last album was a big hit and it's nice to see them in top form after all this time. I didn't they had played Milton Keynes bowl two nights in a row this year (130,000 in total). The biggest audience for a punk band ever! They are making history in their own syle if you think about it.