Data Speeds: AT&T does have a faster data network than Verizon's CDMA. AT&T iPhone 5 will likely be compatible on HSPA+ and the iPhone 5 for Verizon will likely be on LTE. No one knows exactly what the speeds will be but you will not likely notice the difference as a user.
Multi-Tasking: AT&T is only capable of talking on the phone while surfing the web or reading email. Verizon says they are working on a solution but it will likely require WiFi.
Battery: We speculate that AT&T's network might be a bit more battery friendly than Verizon's CDMA network which has been notoriously bad on the Motorola Droid battery.
Tethering: Its not clear who will offer tethering and at what price but we speculate this will be an issue. Most sophisticated users are simply tethering their iPad or Laptops and not subscribing to an additional data plan for the device. T-Mobile's HSPA+ network is most friendly about tethering on the Android G2 and MyTouch phones.
Antenna: Verizon moved the antenna in the phone presumably to fix the death grip problem. However, its not clear if the Verizon phone will still need an iPhone bumper to prevent the hands from shorting out the antenna signal.
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