If you don't want to directly enter a comment, set a review date or assign a context you can easily create a new Item by entering the Item title in (1) and pressing "Return" (2) on the keyboard. To end input without creating another task tap the Hide Keyboard button (3).
The new Item will be added to currently displayed Project, Folder or Meeting and is displayed according to the current sort order in the List View. If you are in a special list view (i.e. "Review Next Steps" or "Review by Context") the item will be created in your Inbox. In the "Review Next Steps" list the Review Date is automatically set to the currently selected date.
This feature is designed to give you a continuous input. This means you can simply enter a new task, press return to create, enter the next task, press return, and so on without a need to tap anywhere else. If you are using an external keyboard (i.e. bluetooth keyboard) you get the most out of this feature as it allows you to "just write down" your task list.
If you want to set more Item details on creation see the Chapter on Item Details Popover.