Apple released iOS 11 beta 4 is only for registered developers who have already installed a previous iOS 11 beta.
There are no major new features in iOS 11 beta 4 for developers. Most changes are related to improved performance and fluidity of the system. Settings that the end user does not see in the form of new features.
However, some app icons have been redesigned. Specifically, three: Notes, Reminders and Contacts. The change is not very outstanding, and can go very noticeable.