Jeff Bennington writes at his blog, The Writing Bomb, how he unpublished his own work after he realised his early writing sucked. In his analysis, he breaks down some common writing problems he identified in his own work, so that we all get to benefit from his experience:
I've read indie authors and many of them are amazing, selling, and getting incredible reviews. Unfortunately, some are not. The reasons vary, but these books suffer because of poor cover art, poor formatting, but most often because the author has much to learn. I know I did. Fortunately, I fixed my mistakes. Well, most of them anyway. Writing is an adventure, and I'm sure I'll be learning twenty years from now.
Jeff lists several key flaws in his first attempt at writing (and subsequent self-publishing), and they're worth looking through to see if you suffer from some of them.
At the end he says, tellingly:
I know, you want to be original. You want to stand out. But listen, dear author; great writers can break the rules because the rest of their writing, plot, and characters are spot on. When you decide that originality means not following the rules, or disregarding them altogether, you have decided that you no longer want to sell books.
This is such a good point. Experts in their fields have earned the right to flaunt rules by virtue of knowing them intimately.