The documents here are the results of a usability study conducted at the beginning of 2008 by a team of three students (Kaisa Anttila, Markku Väisänen and Sami Mylly). They list very interesting things to improve, which prompted me to ask for permission to publish their documents here.
There is a 20 pages text report, as well as 30 slides intended to sum up the outstanding issues the team found.
The text report is at EvaluationAll.pdf
The slides are at finalreport.pdf
Feel free to pick something in the study and write a patch to improve it!
They also worked on studying the leveleditor. The results of their study are slightly less accurate due to them reviewing an old version of the editor, but they proposed a new user interface design that we could base ourselves on at a later point.
Their 14 pages text report for the leveleditor is at walkthrough_report.pdf
The GUI prototype explanation is at GUIexpl.pdf, with explanation pictures: