The short answer is YES. The mobile apps (iPhone, Android, iPad, BlackBerry, etc) are all free to use forever.
What cost the $39 a year is if you want to get access to the full set of functionality.
You can also…
- Subscribe to a calendar of your tasks
- Download your data as a spreadsheet
- Get daily reminders of your tasks through email
- Email tasks directly to your account
- Email a task list to anyone
- Assign tasks to other people
- Set up recurring tasks
- Set up to be reminded of tasks on a certain date
- And more…