Hi there,
don't know if this has been mentioned anywhere else, but I'd prefer it if the add button was not at the top of the list but rather at a fixed place in the menu bar. As it is now I always have to scroll up to the top of my todo list to add a new task.
Another suggestion is to make it possible to fold subtasks. I know this isn't possible in Gmail but I don't think it would hurt to make GeeTasks a little better than Google Tasks.
As to the design: The icon isn't as nice as that of Things, for example, but I think it looks better than many others. As to the rest of the app, I like the screenshots from the "ugly" thread (i.e. the round "checkboxes").
All in all I think GeeTasks is nice, simple and intuitive and does the job!