Ha. It dawned on me today that the only reason I worry about negative reviews of my own novels is because, although I try very hard not to, I let the negative reviews for other authors' novels influence me too much. (I am embarrassed to even admit to such a thing.) Logically, I tend to think others do the same. I must stop this. It is not fair to me or those other authors. There are so many books I enjoyed that many others didn't.
Bottom line, everyone is entitled to his or her opinion. Even if it is stated in an immature, hurtful, or rude way. It is just one person's opinion. It is difficult, as authors, to take criticism lying down when many of us view our books as important as our babies. It is an ugly fact of life, however, that there exist people in the world who actually enjoy hurting others and the web offers a way to do that with little repercussion.
As authors, it is important that we not acknowledge these hurtful reviewers. These are people who enjoy the reaction their review causes. By acknowledging the review/reviewer you have given them what they want. If a negative review has something constructive to say, that's one thing. Learn from it, grow as a writer. If it is nothing but rant, ignore it. It does no good to argue with a fool.