Nice review and after reading it I need to get AI on vinyl!
Your quote below pretty much sums up this album. I like it a lot but it sounds too familiar, too much like AI. While IMO it would be difficult for any of their future material to live up to the AI standard I'm still enjoying 21st Century Breakdown a lot.
"As soon as you drop the needle on 21st Century Breakdown, you're reminded of American Idiot. Lots of muted vocals followed by crashing guitars and drums--they employ this so much, that at times it starts to feel a bit formulaic. "