He's a good singer and writes some nice enough middle of the road pop ballad type of songs.
I guess it depends what you're looking for, it's not something that interests me but I think objectively he's pretty good at what he does.
His music is probably appealing to who are into Adele or Ed Sheeran or something like that.
I think some of his appeal is that he is a bit of a character with sense of humor and doesn't take himself seriously at all, which is actually quite at odds with his music. He seems about as down to earth as it gets and very much not your typical pop star, which I think is actually probably part of the reason why he's having troubles with his health in terms of developing tourettes and anxiety and things, which he said has been brought on during his rise to fame.