Facebook's Hello dialer is an interesting extension of the social service into core telephony functions. That said, the original release was a bit barebones and left a lot to be desired. Version 2.0 (which has come just a couple of months after the initial release) adds some important features and a tweaked interface that should win it a few more converts from the stock dialer app. Chief among these are the ability to filter the contact view to just those contacts with phone numbers, and notifications for missed and blocked calls.
You want more? How about a new "card" layout for incoming calls that lets you answer in one swipe? ("Card" is being used here in a generic sense - it doesn't look like a Holo or Material Design implementation.) How about the ability for other apps to see Hello contacts, for sharing and the like? How about manually editing a contact's profile photo, for that friend of yours who insists on replacing her own face with her newborn child's (COUGH Staci COUGH)? How about support for phones with dual SIM card slots, which finally seem to be making their way to European and North American markets?
Other additions noted in the change log include integrated contact shortcuts and support for right-to-left languages. The Hello dialer is free for Facebook users and works with current Android phones, but not tablets, for obvious reasons.