This song begins the B side of the album so there is a prolonged introduction which is about thirty seconds of manipulated white noise combined with a gong roll that goes from almost nothing (you need the speakers on max to hear the first few seconds up to a loud that would blow out the speakers if they were on full blast) that ends with the vocalists (well, it's all the lead singer, but Queen often mixes multiple tracks of the same person singing) doing a boisterous minor chord in a high falsetto.
The next part is extremely confusing to those who have never heard the song before. There some more vocal chords and then a guitar phrase that just doesn't sound quite right. This quickly goes away when the music gains stability and it is then that it is realized that the earlier part was so confusing because it was being played backward. It's extremely fun to hear the exact same guitar lick backward and forward right next to each other. This is a great guitar lick using rhythmic intensity by using the accenting every three eighth notes thing and uses sequence to show anticipation of the cadence, which is aided by the vocalist in falsetto and this time resolves in a major key.
Finally, one minute in the song and we have the verse. The verse is very simple with basic rhythmic guitar and bass in the background behind mostly eighth note based vocals. The chorus is much more interesting. It consists of a call and response between the instruments and vocalist with the vocal doing half a measure of syncopated sixteenth notes followed by the instruments doing half a measure of straight sixteenths. Then for the end of the chorus the vocalist and instruments join together for a hemiola emphasizing every three eighth notes for two measures. It's always fun to hear a song that dares to have the bass and vocalist play the same line and it is very often effective. This verse and chorus repeat followed by the return of the introductory guitar lick, only forward this time.
Then there is a bridge that is dominated by the drums doing sixteenth note fills in the second half of every measure with the guitar just doing dotted eighth sixteenth rhythm in chords and the vocalist on eighth notes. Then there is a big gong hit again that signals the beginning of what would usually be the guitar solo, though this really isn't a guitar solo. Though the guitar does a lot of embellishing to the rhythm part almost to the point of losing rhythmic stability (the drums keep that), this is supposed to be the "ogre battle". There is a return of the white noise from the beginning as well as non-tonal screaming from the vocalist.
After this the drums transition back to the verse but instead of going to the chorus after the verse, the verse changes and transitions its way to the falsetto major chord that was present near the beginning of the song. This gives way to one last playing of the guitar lick, with an additional part near the end and then one last extended falsetto chord by the vocalists into a monster gong hit that ends the song.
This is a fun song with a great guitar part and the backwards forwards thing is especially great.