Found something weird with Outlook 2013.
This showed up in our Beehive to Exchange migration but it would not be limited to that particular situation.
Let's look at the results first. All of these clients were accessing the exact same contact record on our Office 365 test system, though we have confirmed the same behavior with Exchange on-premises as well (no surprise there since this looks to be an Outlook 2013 bug).
Contacts and Notes (including some data we capture to the contact notes either because of EWS bugs or there's no other place to put it) show up fine in Outlook 2007 post-migration.
OWA and the Surface are no problem.
THEN we get to Outlook 2013:
PROBLEM! Where did the Notes go? The situation seems to only show up if you have a contact created using EWS.
This gets EVEN WEIRDER because in Outlook 2013 you get Notes displayed correctly in the PEOPLE view....
but not in any other view (Business Cards for example):
We think this is fairly definitive proof that Outlook 2013 has a bug in it.