Been setting up GPOs lately for Windows 8, there are serious issues there, for example the homepage URL is no longer where it used to be, it's now a preference, not a policy setting.

Removing the packaged apps is a PITA, you either have to edit the WIM using DISM or run a script to remove them for each logged on user, there is no GPO nor can you remove them from the default policy (as far as I can tell), that appears to be by design.

Some IE10 settings are hidden, such as content filter, that is also controlled by a preference, not a policy.

And so on. Took me ages to figure it all out.