Old line C programmers sometimes don't like references since the reference semantics they provide isn't *explicit* in the caller's code. After a bit of C++ experience, however, one quickly realizes this 'information hiding' is an asset rather than a liability. In particular, reuse-centered OOP tends to migrate the level of abstraction away from the language of the machine toward the language of the problem. References are usually preferred over ptrs whenever you don't need 'reseating' (see early question on 'How can you reseat a reference'). This usually means that references are most useful in a class' public interface. References then typically appear on the skin of an object, and pointers on the inside.
The exception to the above is where a function's parameter or return value needs a 'sentinel' reference. This is usually best done by returning/taking a pointer, and giving the nil ptr (0) this special significance (references should always alias *objects*, not a dereferenced nil ptr).
