Browsing and editing products seems to work fine but when I click "Add" in every product view I've tried MMPD hangs bringing up the dialogue. I've let it sit to see if it eventually comes up and it does not.
See page 34 of the Installation and Administration Guide for Groups and permissions. You may have made the same mistake I did the first time by copying all the Permissions to the right. Some permissions are restrictive and will prevent you from being able to manage data. Yeah I know... this is nuts and at some point in the future we hope to state all permissions in the affirmative.