Personally, I don't understand the complaints about Paul's performance. I'm watching it on VH1 now, and his performance is actually quite grand. And although his harmonies on WMGGW aren't superb, they're not really THAT bad. I especially think Sgt. Pepper/The End was spot on, and rocked the house. I think sometimes that our expectations of Paul are so high, that when we finally see him perform on something, we get a tad let down at times. I'm definitely guilty of that myself. Plus, you have to remember that the man just got off a full-length North American tour. So even at the times when his voice cracks a tad, you can't expect it to be top notch. Give him a break. He's Paul McCartney, but he's still human. But his performance, in my humble opinion, is very good.
PS--Although I think Rod Stewart's vocals on 'All You Need Is Love' were quite awful.