You must break all the rules of painting [*insert "writing"*], but you must also convince me you've had a reason to do so.
— Hans Hoffman
I love this quote. I've read books where something completely unexpected and shocking happens and it's just PHENOMENAL. Maybe the author kills off a main and well-loved character, or maybe they stick a poem in the middle of a chapter or switch POVs midstream or jumps time frames or breaks some other "rule" and it just works. Sometimes breaking all the rules or bending and twisting them in unexpected ways is what makes an incredible book so amazing.
And sometimes it's painfully obvious that the author was aiming for some shock value and it falls flat.
I think there is a time and place for bending or breaking the rules, but it has to make sense....there has to be a reason for it. If it's done for shock value alone it often comes across as being too forced, unrealistic. The reader is pulled out of the story instead of being thrust further in and is left with a sense of "Oh Please" instead of being wowed.
Just be sure you've got a good reason for what you are doing, something that makes sense for the story, and your readers will be captivated.
Have you ever read something "shocking" or rule-breaking that left you less than impressed? Have you read something done so well it left you in awe of the author's awesomeness? :)