What works
Basic entry, filtering, and display of tasks. 

What does not

After using ToDoList a little more extensively, I've found a couple of issues I didn't see before, and updated the impact of another. 

Some task column icons/symbols don't appear, but show a rectangle (symbol is missing, not available). Columns affected: flag, risk, allocated to, track time, and perhaps others. I didn't test them all. This greatly impacts the useability of these columns in the task/tree view, since you can't readily tell what the column is!

The calendar is pretty useless as-is. The calendar entry for the task is unreadable, and the mouseover popup is too narrow to read.

I've had issues with tasks marking themselves completed. I'm not quite sure what is happening, but I try to change the status only to leave the task, come back, and find it has returned to being checked as complete. This seems like it should be a settings issue, but I have never had the problem in Windows, and can't find any settings that are causing the issue.

Filters for "show due by . . ." don't seem to be working fully. Problem seems related to previous completion status issue. 

What was not tested
Less-used menu entries: import/export, task printing. 

Additional Comments

I have to downgrade my rating for useability, due to the issues mentioned.