This is my second Ballard novel and I think that he was caught on a theme and was compelled to write a novel around it. In Crash he obsessed over technology and perversion. In The Drowned World he obsesses over reversions to primordial states--the planet reverting to prehistoric jungle, mankind reverting to pre-civilized social norms, a person reverting from adulthood to the womb. Where I found the repetition of words in Crash to enhance the story, I didn't connect with it in The Drowned World.
None of this is to say that I didn't find the book enjoyable, just that Ballard was less skillful in his relentless pursuit of theme and it took away the impact that comes with feeling what a novel is about rather than it telling you what it is about.
To be fair, this was his first novel. I wouldn't recommend it to someone looking for their next summer read or great classic, but placed in context, it contains the seeds of things I liked in Crash and builds on the skill honed through writing short fiction.