Whoever said that was probably just looking for a reaction because they know so many people like it.
When something is that popular, I bet people think they are being radical when they say they don't like it, like "hey look at me man, I don't follow the trend, take that you band-wagon-jumping losers!" I'm not saying you have to like the book, we all have our own opinion, but you shouldn't knock it till you try it, and if you don't like it, don't make a big deal about it. I don't like Harry Potter because everyone else does, I like it because it's good.