You can give public feedback via comments on individual pages, but you can also give private feedback via the form. The feedback that you provide via this form will not be published.
If you do not know what to provide feedback on then consider for example: What do you particularly like about the Academic Career Visualizer (ACV) and why? What not? Why not? What did not work as you expected? What did you expect? Which other functions or possibilities would you like to see in the next version? What are you using the ACV for?