It’s good, and I like it, and I think I’ll like it more the more I listen to it. It continues in the same vein of American Idiot, i.e., loosely linked concept album with lots of anthemic moments, so if you like the one you’ll like the other.
That said, I’ve seen reviews that say it tops American Idiot, and I don’t think that’s even close to being true. Even if 21CB has more of thematic through-line than AI (which it does) and the songwriting is close to par with that album (and it is), the fact is AI is substantially more significant, both for the band — it was the album where a fading set of yesterday’s heroes said “fuck it,” went for broke and watched it pay off big — and for its time, in which its snarly WTF? attitude perfectly encapsulated a generation’s growing disgust for Bush’s America. Lots of musicians were pissed off about Bush in 2004, to be sure. But Green Day was the one that hit the sentiment right out of the park and went multi-platinum with it as a consequence. Right place, right time, right band, right album. Nice when it happens. It doesn’t happen for everyone.
So as good as 21CB is, at the end of the day Green Day’s going to be remembered for two albums: Dookie, which is the album that got them their career, and American Idiot, which got them their career back, and will probably (for what it’s worth) get them into the Rock and Roll Hall of Fame one day. As long as we’re clear on this, we’re all good.