Google has added a bunch of new features to Google Classroom. All of the features added are things that I've heard teachers request since last year's initial launch of Classroom.
The most significant update to Classroom is the integration of Google Calendar. Now when you create an assignment in Google Classroom the due date will be automatically added to a Google Calendar for the class. You will, of course, also be able to manually add events to that same calendar. This feature will be rolling out to all Google Classroom users over the next month.
A new feature that is live for all Google Classroom users is the option to re-use any assignments, announcements, and discussion questions. So if you have items from a class that you taught last year, you will now be able to quickly copy them into this year's class.
To further encourage online discussions, Google Classroom now allows students to reply to their classmates' responses to the discussion questions that you post in your classroom. This sound create a more message board-like discussion environment. You can also turn off that feature if you don't feel that it will be beneficial to your students.
You've always been able to link to Google Forms in a Google Classroom post. Over the next month a new feature will be rolled out to allow you to attach Forms to announcements and assignments. The attachment will also include an option to link to the Form responses within Classroom.
Finally, you can now "bump" a post to the top of your Classroom's stream. This is similar to making a blog post sticky so that it always appears at the top of the page for students to see. Bumping a post could be a good way to make sure that students see an important message from you whenever they sign into your Google Classroom.