“The Beatles was the best band in the world. It’s difficult to follow that,” McCartney explained. “It’s like following God. Very difficult unless you’re Buddha. Anything Wings did had to be viewed in the light of The Beatles. And the comparisons were always very harsh. Denny Laine wasn’t John Lennon. Henry McCullough wasn’t George Harrison. That was inevitable. The interesting thing is that looking back on some of the work, some of the stuff, it’s better than you think it was, but because it got such harsh criticism… from me.”
But despite this success, Wings have always been widely ridiculed. And now it appears that Sir Paul agrees with his critics.
Speaking to broadcaster John Wilson in front of an audience that included Brad Pitt, James Bay and Paul Weller at the BBC's Maida Vale studios, McCartney said:
"We were terrible. We weren't a good group. People said, 'Well, Linda can't play keyboards', and it was true. But you know, Lennon couldn't play guitar when we started. We knew Linda couldn't play, we didn't know each other, but we learned. We had some funny experiences. Looking back on it, I'm really glad we did it."
"It was very depressing. You were breaking from your lifelong friends, we used to liken it to the army - we had been army buddies for a few years, and now you weren't going to see them again.
"People said to me, 'Get a big supergroup with loads of stars,' but for some mad reason I wanted to go back to square one and do it as we did in The Beatles."
One of the main differences was the level of responsibility he had. He said he had less time to focus on his music with Wings because they didn’t have a manager. So, he had to do everything, including songwriting. He found the experience to be the “biggest headache.”
“I think it was okay, but I think I never quite had the interest that I had during that sort of dream period around Sgt. Pepper and Rubber Soul, when I was doing something… See, with Wings, I was now the band leader, the business manager, the this, the that. We didn’t have Apple, we didn’t have Epstein, we didn’t have anything. It was me doing it all. That was the biggest headache – that’s difficult.”
“In The Beatles, I’d been free of all of that. We had a manager, we had three other great guys… I think there was like a prize period when I was playing my best bass, and I think after that I had so much to do that I wasn’t free to just do the bass. I could concentrate everything on writing the song, singing harmony with John, or playing the bass, pretty much my role, or maybe playing a bit of piano or guitar or something.”
Source. VMZ - Cheatsheet