Here's some things I notice at first glance that contribute to it's incomplete feel, imo:

- Lack of hierarchy among elements

- Inconsistent layout from page to page

- No typesetting, paragraphs are squished together in a dark font

- No indication of what the current page is beyond the browser tab title

- Heavily contrasting colors in certain areas like call to actions (white-on-blue) that will bleed on cheaper displays

These are all things that if fixed would improve usability while adding zero decoration.