The report should show a much clearer structure according to topic materiality. This concerns the formatting & matter-of-factness of headlines and index, but also the order and weighting of each material topic. The most material topics should be the most prominent.
The report could be much more visually appealing. A version with cross-references, more charts and graphs (not only at the beginning) would make it easier to read and see key figures at a glance.
Achieved, unachieved & future goals could be displayed more graphically as a summary for each material topic.
As usual, the PDF version is not navigable at all. A HTML/Browser version would make it much easier to move across the report and make the necessary connections between topics.
add references under paragraphs, to which GRI-guidelines is referred to
the overview should be on the beginning and not only on page 4, since (at least for me) it makes no sense to put the quantitative targets and key indicators before the overview of the report
remove empty pages to reduce size of report, they maybe make sense in the printed version but not in the online report
include links for further readings/more interactivity
maybe difficult for laypersons and not all stakeholders, therefore the texts could be somewhat simplified or at least supplemented with infographics