It's not that I'm necessarily going to agree with the negative reviews. But I definitely find them much more useful.
It's a sad state of affairs when we're told that there's only one correct opinion about a particular piece of media and dissenting views are "wrong." We lose the deep insight that comes from looking at who likes and dislikes a piece and why. And it's hard to truly like something when liking it is presented as the only correct choice from the start.