Eli Bendersky's website Told by one of the researchers responsible for the discovery of the structure of the D.N.A. molecule, "The double helix" is mainly a mixture of auto-biography, obscure chemistry and a story of young researchers doing their work.
If you're not seriously into chemistry / biology this book's technical details, though not many, will be difficult for you (I barely understood it even with some editing comments that tried to clarify things). Make sure to read the Wikipedia entry on DNA first :)
Unfortunately, I expected it to be a pop-sci book, and got dissapointed. As a pop-sci book it's pretty bad - it's more of an autobiography.
Additionally, I didn't really enjoy Watson's style. It's quite dry and doesn't do a good job of "transmitting" the author's excitement to the reader. Someone like Simon Singh would do much better with this book.
The only really interesting thing I found in it is a curious exposition of the lives of researchers, from a different angle than is usually told. Other than this, though, the book has been a waste of time.
I only recommend it if you're a molecular-biology enthusiast eager to hear the details of Watson and Crick's discovery.