Hello, you can see currently filed issues on the bug tracker to get an idea of what people want to see improved: https://caml.inria.fr/mantis/view_all_bug_page.php (set the ‘Category’ to ‘ocamldoc’ and then click ‘Apply Filter’).
For example, here’s an (in my opinion) interesting case where the HTML output is fairly clumsy and not very accessible: https://caml.inria.fr/mantis/view.php?id=7634
I brought up the topic of a design refresh a while back, I haven’t had time to work on it recently though. If you’re curious: Proposal: ocamldoc should generate a table of contents in each module page