Contrary to popular belief, Paul was the rock musician in Beatles, even if John was more of a rocker in attitude. He wrote Sgt. Pepper's, Helter Skelter, Lady Madonna, Back in the USSR, to mention a few. Knowing that, the sound and feel of Back to the Egg shouldn't be so surprising. Because this is hard, heavy and fat rock 'n roll. One might get decieved by the sheer pop of Getting Closer, but the brutal riffs and vocal of Spin It On soon takes you into a somewhat harder and darker terrain.
The laid-back softness of London Town are completely absent, and even in the ballads, you can sense an edge of rusty metal in Paul's voice.
Wings showed a lot of strength with this recording, but it was a far cry from the sales it deserved. As of now, it stands out like a gem in the Wings-catalogue, perhaps even surpassing the classic Band on the Run.