Actually, I agree. The Reference Guide and all of the other reference guides (digirack, digibase, etc) are very good instruction on how to use the program and best of all they are free.
I would, however, also recommend some good books:
Producing in the Home Studio with PT which covers much more than just PT
and
PT Visual Quickstart Guide which, if you have the print edition of the newest Digizine, you can clearly see on the desk at Trent Reznor's studio .