I can’t, for instance, control the headings for the custom fields in WP, which makes it hard for clients to understand what value should go in a custom field. In EE, I can not only provide a heading, but instructions.
with some backend coding you can design a custom interface for this sort of thing in wordpress. Like you stated the custom fields in WP can be a little over the head of the average user, using the right keys, adding the correct information with the correct code or information. To overcome this and dummy proof everything I had to create a custom interface that allows users to enter text or a url or whatever and everything is taken care of by the code which auto creates a custom field for each item.
not really an endorsement of WP, since having to go to such lengths to simplify the process of adding a post or content when the needs of the website are more than basic blogging can greatly increase the development time of a project.
anyway, I’m rambling when I need to be getting up to speed with expression engine.