If you think that the STL will bring the end to the C++ standard library, I think you might be wrong. I don't know if I was wrong or not, but as a programmer who had grown up with the standard C++ library, I believe that there are a lot of life left in it. I started my career with C++, not C, but I do know that the standard library is the bridge that connect C++ and C, without it, anyone who come from C to C++ will have a lot of problem.
Because of this, what you need is a reference that cover all aspects of library in great detail. And I think this book had done a fine job with this. Like Mr. Plauger own "Standard C Library" book, this book's not just telling you what each function do, but it also provided source code for all of them. So, what is a better way to study and understand the standard library?
For me, this book has its place next to Stroustrup's The C++ Programming Language and Josuttis's The C++ Standard Library. (And now, I'm waiting for Mr.Plauger's upcoming STL book )