The thing about "When I Come Around" that makes that song really cool is the sound and rhythm of the guitar. The composure of the music really works. Classic Billie Joe palm mutes, along with that Dookie Distortion that we all have come to love. All of Dookie is recorded using guitars and basses down tuned a half step so that makes the guitars sound allot cooler too. I have heard that song covered a hundred times by a hundred different artists, but I have yet to hear someone get the guitar part exactly right. It usually is just play straight with no palm mutes or pauses at the right intervals. Mike and Billie really play great together on that song. I agree with you that the lyrics aren't the strongest on the album nor is the chord structure. It's played, as far as finger placement on the fret board, in G Major but since the guitar is tuned down a half step, it's actually in F# Major. Most of the song repeats the chords: F# C# D#m B throughout the song, except for the chorus which is: G# B, G# B. That power-chord pattern is used in half of the songs ever written. Maybe, that's a stretch, but the band surely wasn't reaching very much when it came to that aspect of the song, but that can be said for most any Green Day song. After all, complexity is not why we listen to GD. We listen because their music sounds cool and is full of energy and emotion. That can't be measured in music theory. It just works.