While I might agree with the above, it isn't too much to ask a professional musician who commands high ticket prices to actual work on his skills and sing mostly in tune and on key. He does have in ears these days so that's a big difference from the earlier days they toured where perhaps he couldn't hear himself.
Also unlike some other singers it doesn't sound like he's blown out his voice (ala David Coverdale), it sounds like he doesn't work on it, sings stuff he cant hit and barely knows the tunes and the melodies he wrote to the songs. I mean really, if you had a guy come to try out for your band as lead singer and he sang like that you'd take a pass I'm sure. The rest of the criticism I think the above applies.