I don't own an iPhone (see my previous post), but offering a $100 credit when the price drop was $200 seems insulting.
And I'm surprised that the outcry came as a surprise to Apple. It would have been so much better to have announced it at the same time as the price drop, not a day or two later. And since it's a store credit, not real cash, the "win 'em over" manuever would have been a $250 credit.
When you screw up, a +1 recovery (fix it plus a little extra) is the right answer.