The only real problem I have had with my DX is the phone confusing contacts.
One example is I added a new contact named "Bobby" and it added it to an exsisting contact "Rob".
Another and more annoying one is with the New Message Widget. I have a contact named "Jen" and "Jenny" in my phone. Completly different contacts in the list. When I get a text from "Jen" the widget displays its from "Jenny" and will quick repond to the "Jenny" contact. But if I got into messaging, you can watch the phone change the sender to "Jen". This happens with all contacts that are similar.