I think Jon's voice isn't that bad as many think. There are songs like Satellite or others, which are kinda high and which sings quite good.

BUT, what sucks big time: The way Jon sings live! If I listen to Radio saved... from this year, he sings this great rock song like a ballad! Beginning from the verses of the chorus. He doesn't even try to scream some words, he sings every single word like a ballad. And that's what makes the songs boring live.