Well, not everyone seems to hate it, but it's a very love/hate movie as far as people's responses go.
And I LOVED Scott Pilgrim
It was so fun, colourful, and full of energy. The wonderful visuals, magic-realism-esque scenes, the tying between the theme and plot, it was all wonderful.
I loved Scott Pilgrim too. I actually thought I was going to hate that movie, so I was pleasantly surprised by how much I wound up enjoying it. I didn't think it was a "hated" movie though - I've heard nothing but good things about it.