I think you need a reference manual for the language. Now most of what most people (me anyway ) would consider language constructs are described in Kernel and Kernel.SpecialForms as if they are function/macro calls, not as language constructs. I know that this is what they really are, and that sometimes this is important, but for describing "the language" this does not make sense. Yes, there are tutorials and books that are good but somewhere I need a reference of the language, or at least what I perceive as being "the language".
The Erlang reference manual is not too bad in this respect. It is not a formal language description but it systematically goes through all the language constructs. I can find each construct, or group of constructs, and see what they should look like and what they do. For example I can see all the arithmetic operators grouped together with a simple description of what each does. I can also see the relative priorities. You can also link into the module documentation when necessary.
I think being able to group constructs is a useful thing with a reference manual. For example I could see everything about defining macros in one place and get better feeling for how they work together. Or everything about modules in one place.
Another problem with Kernel and Kernel.SpecialForms is that they differentiate between functions and macros which is generally not that interesting for users. It is correct and relevant when describing these modules but not when describing the language. For me the user it is not interesting that
case is a macro.
I think the difference between a tutorial/book and a reference manual is that the reference manual is a more structured description while the tutorial/book are often more example driven. You need both but for different things.
I hope this wasn't too garbled.