Quick review of code at http://potato.lsi.upc.edu/projects/moodlewebservices/browser/moodle

1/ do not include all libraries at the top of externallib, always require in each method separately - the externallib libs are included during each upgrade and the libs take up a lot of memory even when they are not used at all

2/ new DML code does not return $success, instead it throws exceptions; for example $if ($DB->insert_record()) is useless now

3/ use delegated transactions - see group/externallib.php

4/ do not use throw new moodle_exception ('noexistingrole'); instead use the new MUST_EXIST parameter in get_record() and similar

5/ do not create new localised error strings when not necessary

6/ create_course_categories - check capability in parent category, not just system context

going to add more here when these get fixed