Is it success? Is it the amount of books one sells? Is it how many fans one has?
James Patterson is a prolific writer. In fact he has written more books than Stephen King, John Grisham, and Dan Brown combined. Very impressive, yet in an interview for USA Weekend Stephen King referred to James Patterson as a 'terrible writer (but he's) very successful. Patterson's response in a Wall Street Journal was "he's taken shots at me for years. It's fine, but my approach is to do the opposite with him -- to heap praise."
What about fans? Mickey Spillane, a prolific writer of years past said: "I have no fans. You know what I got? Customers. And customers are your friends."
So what's the answer?
The way I see it a writer, or anyone as far as that goes, has to try to be the best that they can be. No matter how well one writes some are going to like their work, and some are not. One just has to keep trying and trying to be better and hope that more people will like their work than not.
I think for me I need to write, and write, and read, and learn, then write some more. I'll put in the work and hope for the best. When some big time critic begins to criticize my work I'll know that I'm almost there.