I am running iOS 6.0 on an iPhone 4S. Using the Settings -> Notifications -> Toodledo menu, I configured the Alert Style to "Alerts". I then created a sample task and set a due date and time for 10 minutes from now. My iOS toodledo app is setup for "Task alarms come from device".
After 10 minutes had passed, I got no sound or alarm of the task. When I pulled down the notifications menu, the task was listed. However, the alerts don't seem to be working.