Like all Drupal 8 module development, creating forms isn't quite as straight forward as it has been in the past using the hook system. Symfony has changed the way that forms get created and called, adding a layer of complexity with the move to object-oriented code. As far as the actual form API, several HTML5 form elements have been introduced, but in general it should be a pretty easy transition for most people.
Drupal 8 Module Development, Part 2: Forms
А ведь некоторые считали, что это с шестерки на семерку надо «переучиваться».
