"Shared Documents" in the Client File has been replaced with "Documents". Clicking this link will take you to the client's home folder in the Documents section instead of the client's "Shared Documents" page. The home folder contains both private and shared documents you've uploaded to the system for that client.
At the top of the client's home folder, there is now an "All Shared Documents" link. Clicking this will take you to a page where you'll see all documents shared with the client and documents the client has shared with you: