Although everything I have read by Ballard is excellent, I would recommend this book as a starting point. The author weaves autobiography with fiction in a compelling way; in some places the novel hints at the dream-like sequences that he has deployed in other works, but the story is firmly grounded in reality. The most apparent theme is that of survival, but I don't think Ballard wrote this with any kind of agenda; perhaps that's what's so refreshing about it.
One of his greatest talents as a writer is finding moments of beauty in what, for lesser writers, would be mires of ugliness. Ballard's voice is thoroughly modern throughout, despite the book's retrospective narrative: you can instantly tell this is the author of 'The Concrete Island' or 'High Rise', despite how remote those novels are from the second world war.
Those who have seen Spielberg's film will be thoroughly shocked: there is little sentimentality here, and the story is quite different in its later stages. Not that the film is a poor adaptation - rather, it's a seperate entity. Always read the book first!
It's wonderful that an author can use his past as a starting point for fiction, rather than being either grounded in it or evading it. It's hard to tell what is fact from what isn't, and surely that's a good thing.
Finally, I must stress that this is a book which not only survives several repeated reads but seems to require it.