Roger Orr has written about the history and use of auto in ACCU's Overload 115:

Auto -- A Necessary Evil?

by Roger Orr

From the article:

The keyword auto now lets you declare variables where the compiler provides the actual type and the programmer is either unwilling or unable to name the actual type. The keyword can also be used in function definitions to let you provide the return type after the rest of the function declaration, which is useful when the return type depends on the type of the arguments.

As with any new keyword there are questions about usage –- at two levels. First of all, where and how are programmers permitted to use the new feature. Secondly, what guidance is there to sensible adoption of the new feature. I intend to start with by answering the first question and then subsequently focus on the second.