I enjoyed her first collection, Saint Lucy's Home for Girls Raised by Wolves (hardcover), very much, though I cared for some stories, such as the title story, far more than others. Indeed that title story alone was worth the price of the collection. Thus, even though I hadn't liked the swampy stories from her collection, I bought the hardcover of her novel. I didn't enjoy Swamplandia, and for the reasons you state. It was an enormous disappointment and I was sorry to have bought it. I think she is a great talent, but has a ways to go.
Thank you for your review, which helped me avoid a purchase I would have regretted.