To me I found a rather annoying "bug" with the Contacts manager.
I
filter which Google/Gmail contact groups should be displayed, so that I'm not constantly scrolling through Businesses, Business contacts, Extended & Overseas family, etc.
BUT the search option doesn't find them unless they're
filtered in. This is clearly a mistake, as I could do this with my previous phones (Galaxy Nexus, Droid 1). If I go to the
Groups tab I can still go to the groups in question and find the contacts, so I know they're on the phone,
but there's no search option from within the groups view, so one can only scroll!
A secondary related problem is that you can only edit one of these contacts if they're
filtered in. :-\
This is only mildly annoying, because I don't edit existing hidden contacts as frequently.