The form builder used to be a list of collapsible fields. It is now a canvas with a library you drag fields out of, in a workspace shaped like the other builders in the app.
A form can ask for any field the CRM already knows, including your own custom fields, so nothing has to be defined twice. Questions can adapt to what someone answered earlier, and visitors can attach files.
A submission also does more than create a contact: it can create companies, custom objects, deals, tasks and tags, and a message goes back to whoever filled the form in. Forms and their submissions now live in the same list screens as everything else, with filters and saved views.