I think people are forgetting that the only way you could have an iPhone was to have an unlimited plan. There were plenty of people who didn't want to spend $30 a month for unlimited, but they were forced to. ATT got tons of extra money when people weren't using that much data, and didn't want an unlimited plan. Now they are punishing their long term customers by trying to make them switch off of their unlimited plans.
Problem is, they never made it enticing enough to get off of the unlimited plans. Sure, you could spend $15 and get 250MB, but 250 MB goes quickly. The only other step was $25. At that point, there was little financial incentive to get off unlimited for $5 a month. Now the new shared plans are more expensive for a large majority of people than they are currently spending, and they are now throttling those loyal customers who were forced into unlimited plans originally, in essence taking away the unlimited plans anyway. For them to limit Facetime over cellular is horrible since it isn't really unlimited data. I hope ATT loses big time on this.
I've also thought about switching, but the Verizon iPhone can't do surf and talk at the same time. There isn't a good alternative.