There's gonna be some rockin', but not really much else.
In 2011, Apple largely left 2010's iPod nano alone, though it did slightly tweak the software to embrace a popular use of the tiny touchscreen device as a watch replacement. A small cottage industry spring up to design and sell all manner of iPod nano "watch bands," but Apple has now abandoned that idea in favor of giving the seventh-generation iPod nano a larger, 2.5" touchscreen capable of playing videos.
Beyond the new screen, the addition of Bluetooth 4.0, and the switch to Apple's smaller Lightning connector, however, very little of the internal hardware changed in the 2012 iPod nano. Software remains largely the same as well, with a similar collection of "apps" all provided by Apple.
Apple has a history of moving in interesting (if odd) design directions with the smaller iPods, and then changing its mind. Remember the buttonless third-generation iPod shuffle? That design didn't fare too well, it seems, and Apple again sells an iPod shuffle with buttons. How about the third-generation "fat" iPod nano? Apple thought a sideways screen would be a good way to add compatibility with video and then-new downloadable iPod games, but the fourth-generation nano returned to the taller "candy bar" design.