Here are some of the feature that you are expecting from the new iOS 6 update. Actually it's kinda nifty to have if I do say so myself. Normally when a calls comes in we can choose to 1) accept 2) decline 3) ignoring it. But now with the new iOS, we have the option to 1) Reply with Message 2) Remind Me Later. In Reply with Message, we can choose to reply with a standard message of 1) I'll call you back 2) I'm on my way and you can even customize what you want to reply to the caller.
As for Remind me Later, we will be reminded 1hour later to call back to the caller via the Reminder app. You can choose between a few choices stated above but some of the requires you to set the Location service to be on to get the right notification.
Next we have the Do Not Disturb feature. It means that you can now stop all calls from coming in. Hence you can divert your calls to voice mail or notification only. You can toggle this feature through Settings. You can also Schedule when you wanna Enable this function. You have the option to only let certain people to call in via "Allow Calls From" feature. You can use the Group or Favorite list of people you had created in your phone to this feature. Which is really neat, since I had created a few groups in my own contact list :) Another feature is called "Repeated Calls" which means that it will allow the caller who called you repeatedly within 3 minutes will get through to you as they treat it as an emergency call. No there is NO BLACKLIST feature yet. But I think a lot of you guys out there would really like this function on their phone :)