I have no desire to get into a personal argument, but I would like to point out that one contribution he has made for me that have not seen elsewhere is that he has chosen to use Emacs as a text-processing scripting environment in preference to Perl or Python or some other scripting languages. Without commenting on issues of style or idiom I found his write-ups of this experience using the text-editing primitives of Emacs to be useful and interesting.
For example, consider:
"Text Processing: Emacs Lisp vs Perl" http://ergoemacs.org/emacs/elisp_text_processing_lang.html
"How to Write grep in Emacs Lisp" http://ergoemacs.org/emacs/elisp_grep_script.html