I'm not wowed by "21 Guns" based on 2-3 listens now.
Granted I didn't have the chance to give it my undivided attention, but nothing on the album blew me away on the first listen. Instead it seems the songs are more designed to advance a concept album rather than stand alone as truly great songs. Really it just felt like
American Idiot 2. I'm sure my opinion will evolve positively over time, though.
I perceived Beatles influences on "Last Night On Earth", 70's arena-rock sensibilities on "21 Guns"
I didn't read your review or any other album-centric comments before listening to the whole thing myself, but I too recalled a John Lennon-sung Beatles piano ballad when hearing "Last Night on Earth." The immediate '70's arena-rock sensibility I heard on "21 Guns" came courtesy of its "All the Young Dudes" ("Twen-ty One Guns") like melody.
The other stolen melody I noticed is all over the intro and outro of "Before the Lobotomy." Totally lifted from Dexy's Midnight Runners' "Come on Eileen":
Dreaming
I am only dreaming
Of another place and time
vs.
You're grown (a grown up)
So grown (so grown up)
Now I must say more than ever
Or if you like:
Singing
I can hear them singing
when the rain had washed away
vs.
But not us (no never)
No, not us (no never)
We are far too young and clever