I really like this addon, particularly because when you are on a gmail tab, if you add a task via the + button (in the top bar, not at the bottom of the list), you can add the email as a task (and it will link them email to the task).

To get 5 stars it would be good to see the "Add Email As Task" link show up whichever way we add a task (it currently doesn't when you add task from the bottom of the list), and have it load more quickly when I click the button in the firefox menubar (at present it takes about 1 second to bring up the list).