The two big issues that I faced were with the OR statements and the IS NOT statements.
Filtering by OU is a heck of a lot faster than filtering by groups.Let’s say you are currently deploying network printers with Preferences.Because you love efficiency, your printers are set to Create.As with any Group Policy based changes, use a test Organizational Unit to confirm and test changes before making them live. Right click Group Policy Objects and select New, give the GPO a meaningful name, this does not link it to an OU so will not affect any computers or users. If you create at a live OU level, any changes (and mistakes) will be deployed if you’re unlucky enough for the computers or users to perform a Group Policy refresh as you’re creating the GPO. Expand Computer Configuration, Preferences, Windows Settings and head down to Registry.Example 1 You have made some changes to HKEY_LOCAL_MACHINE on a reference machine, and would like to deploy the same registry settings to an OU of computers. Always link the GPO later, when you have tested it. Right Click and select New, you will be present with 3 options. Most of the time, our issues will come down to a handful of items and misconfigurations.As awesome as they may be, Group Policy Preferences (GPPs) gave us a whole new set of challenges and a few new ways to troubleshoot.For your clients to reapply the setting, you will need to change your setting from Create to Update or Replace.This same problem applies to other Preference extensions, most notably: Power Options and Scheduled Tasks. If you haven’t already, consider enabling Group Policy logging for certain Preferences.Machines running Windows 8 that aren’t a member of those two OUs will still have this preference applied to them!To get around this, you can use the blue up/down arrows to reorder the items.