Exactly, I only heard about him from hearing about "How terrible he is", and like I've looked at his videos, and while I didn't really love his videos or anything, I fail to see what was so hate-worthy about him.
Terraria Community Forums
Ashyrae
I've met PewDiePie personally - he tends to be a /bit/ egotistical at times, annoying at others, and then the rare moments where he actually behaves like a normal human being. Don't particularly like him, but don't hate him either. *shrug*
aWolfen
To me, I think that he believes it's more about him playing the game, and people come to watch him. Instead of the game, which should be the obvious focus instead of his incredibly absurd reactions to everything.
Ironically enough, that's how I discovered about him; people just aggressively complaining, so at least some of his popularity is attributed to people trashing or saying negative things about him.