The numbers are fine, but selling this as a 'deal' for people is what is outrageous. Specifically, that $20 a month charge for tethering is beyond ridiculous. You're paying $20 a month for the right to use the same data you're already paying for in a different way. This is completely preposterous. I wish I could take it as a sign of impending expiration of ATT wireless exclusivity, but why would they roll out a severe plan right before things are going to get competitive.
Yes, but as it stands, to pay for legal tethering (aside from the iPhone) it would cost you $60/mo on any carrier. This new plan equates to $45 for 2GB with tethering included, and $10/mo for each additional GB over that. That equates to $65/mo for 5GB, which is close to their 'unlimited' cap now. Just about the same price for the heavy users. So for those will tether but no go insane with it (98%), it will save you a boatload of money. For those who do go tether-crazy, it will only cost you in those months you go over 2GB, and still not be that much more than you were paying before.
I mean, far be it for me to defend AT&T here, but I think these plans are truly great. I pay $30 for my wife's iPhone data, and she hardly ever uses it (uses it mostly for expensive medical programs as a Critical Care PA). I use mine a LOT, but also mostly over wifi. Together we will soon spend what we currently spend on only one of our data plans. That's a 50% discount. A lot of people will save the same money here, especially those family plans with numerous smartphones.
Also (IMO), the losses from the unlimited plans will be mitigated by the gains from tethering plans and new smartphone customers as a result of the lesser $15/mo data plans. It's a smart move on AT&T's part. They're going to make more money overall, while most individuals who already have smartphones will save.
In the end, with the advent of the tiered data structure (which I side with Nip on being the rip-off it still is overall), the age of the standard handset is soon to be a thing of the past. Whereas before only a small portion of cellular clientele used smartphones and the majority had 'feature phones', the ratio is reversing itself rapidly. It's not perfect and could be cheaper, but we will all save a good chunk of change with these plans.