Here, I'll review the hell out of this track.
21 Guns on Guitar is pretty linear, but it is fairly entertaining.
It mostly makes for an easy FC, however its still enjoyable.
For the intro and the verse, you're pretty much playing some easy chords with a easily manageable rhythm, without any real tricks in the patterns.
The choruses aren't too different in terms of difficulty, but the chords and the song itself is still entertaining enough to keep your attention.
There isn't really anything too crazy for the rest of this song, the solo consists of some fairly easy-to-hit notes that are quite easy to FC.
Overall, this song is simple, yet entertaining and not too boring at all.
If your mainly a guitar player, this song doesn't have a whole lot to offer, yet is still enjoyable, especially if you enjoy this song. If you're looking for more of a challenge, however, you may want to look at a more difficult Green Day song, such as East Jesus Nowhere.