The 54-page release notes detail known issues and bug fixes.
Don't forget that NetApp University runs online training sessions that cover items such as Protection Manager and Provisioning Manager.
UPDATE: The Operations Manager Storage Efficiency Dashboard Plugin, downloaded separately, is a new script for 3.8.1 to graphically display space savings. Available now for both Windows and Linux servers running DFM 3.8.1 (see above link for details).