I agree -- a great module, great docs. Even better now that it supports cell formatting.
Minor minor minor gripe: the format objects appear bound to a specific sheet... that is, if you have multiple sheets open for writing, you cannot simply define one set of formats (eg fmt_important = bold and red, fmt_header = bold and underlined, etc) and apply them across the board to all open sheets. At least I couldn't get this to work... maybe I missed something.
Overall, a fantastic piece of code.