How to show/hide "printer-friendly version" link according to workflow states?
One way of doing it is by using hook_node_view_alter(). For example, you would put the following code in a custom module called hideprint (see many tutorials online on how to create a custom module). Be sure to dpm() the array $build when you are testing the module to correctly check the value of field_review_workflow.

function hideprint_node_view_alter(&amp;$build) {
  if ($build['field_review_workflow'][0]['#value'] == TYPE_VALUE_FOR_NOT_FINISHED){
    hide($build['links']['print_html']);
    hide($build['links']['print_pdf']);
  }    
}