I don't like him.
His songs are boring and not very good.
When I've seen him sing on TV Shows (Not music TV, but other shows), like the X Factor and he was on the Graham Norton Show, he's rather bad at it.
He doesn't sound good when it's recorded and he adds whatever auto-tuning to it, but it's even worse when he's doing it live or un-edited.
And he's a roostery little brat.
He has an annoying voice too, when he's not singing.
Generally, I just don't like him.
And not due to his fame and popularity or wealth, but just because I don't like his music or his personality.
I'm allowed to judge celebrities. It's one of the factors that makes a person a celebrity, the being judged.