It was controversial if you cared. The Beatles were generally mistrusted by the right for being a rock’n’roll pop band, drug use, foray into hippie culture, etc. Many right wing publications called them communists, pro-Soviets (because of Back in the USSR), and pro-Maoists (despite the Mao verse in Revolution). “Medium subversives” was thrown around, meaning they were stirring trouble but weren’t deemed a major threat. The right also took issue with Harrison’s “Piggies.” Listen to the lyrics and see if you can guess why.

The left wing had a more interesting response. Ramparts branded “Revolution” a "betrayal", and the New Left Review said the song was "a lamentable petty bourgeois cry of fear" – that’s from Wikipedia, mind you. The Beatles, despised by the right for being too leftist, was now being called out by the left for what they saw as a rejection of the change, radicalism, etc of the late 60s counterculture movement. “Street Fighting Man” by the Stones was better received (by some) as a revolution song.

John was the real mover and shaker. Read “John Lennon – The Life” by Philip Norman. His post-Beatles history is incredibly interesting. He and Yoko were harassed by the FBI (encouraged by Nixon) to such a degree that John became anxious about someone watching him or tapping his phone for the rest of his life. Much of that was due to John’s post-Beatles activities, but you could certainly argue “Revolution” paved the way.