Several things I've read lately on various writing sites, critique sites, and agent sites and blogs (such as the the recent #queryfail run on Twitter, which is coming again April 17th) remind me how important it is to have a tough skin as a novelist. The classic stereotype that describes an artist as "sensitive" or "moody" really has no place here. For one thing, there are so many ways one can, and will be, criticized. There are writing group crits, agent rejections, and editorial suggestions, demands, and rejections. And if you are lucky enough to make it to publication, there are reviewers who will hate your work, readers who think you're insane/a hack/a moron, and your own inner critic, who will suddenly discover every teeny, tiny piece of crap writing you couldn't see before the minute your book hits the shelves.
The criticism can fly from many directions at once and be scathingly harsh. And if you want to succeed as a novelist, I truly believe you need to learn how to take it as objectively and unemotionally as possible, because it's an inevitable fact of life. Deal with it. Some people are going to hate your writing. Maybe you are a talentless hack. But if you truly love to write, none of that will matter too much. You'll keep at it regardless of what the critics say. If you write because you want fame, glory, and money, you're sadly disillusioned and the critics will, eventually, get to you. Unless you're a total egomaniac.
Criticism can also be an extremely valuable tool. Harsh as it may be (and sometimes it's downright cruel!), it's important to listen to every tidbit of criticism (both the good and the bad) and weigh it as objectively as you can. Easier said than done, at times. Partly because objectivity is often blinded by emotion, and partly because not all criticism is useful or even valid. Learning to decipher the various comments and feedback, and figuring out what's worth considering and what should be ignored is a difficult lesson. Setting aside your emotions long enough to take the valid criticisms to heart can be even harder. But if you can master it, you will improve as a writer. You will benefit from your mistakes. You will strengthen your prose and your character development. You will learn to trust your inner voice more, and better understand how to interpret those gut feelings about your work. It will become easier to acknowledge and deal with your weaknesses, and to identify and enhance your strengths.
And maybe, just maybe, those critiques will begin to shift from primarily negative to primarily positive. Harsh judgments will be replaced with accolades. The rejections will become fewer and less frequent. And your love of the craft of writing will grow stronger.