Although the changes are not that large, because the essential features of the current forum like levels and marking a best answer will still be available in the new forum.
Moreover the new product forums has also got some new features that users were keen to look for such as:
(1) Adding a “Me tool”: it enables you to vote any particular question to share quickly that you are also interested in respective question.
(2) +1: with the plus one feature you can easily give +1 to your favorite topic.
Check out the screenshot of new design: