What iOS Devices Are Compatible With iOS 6?
The iPhone 5 and iPhone 4S offer full iOS 6 support. The iPhone 4 is also supported, but with some features limited. Same for the iPhone 3GS, but with even more limitations. Old iPhone models are not supported.
As for the iPad, the iPad 2 doesn't support a couple features but is otherwise compatible. The first generation iPad is not iOS 6 compatible.
The 4th generation iPod touch or newer will support iOS 6.