According to some gathered data from forums with customer reviews and other technoblogs, seems like the new iPod nanos meet some screen problems that can be serious.
More than a dozen people have reported the issue on Apple’s Support forums, with most reports saying video appears tilted around 3-4 mm to the left. Apple is replacing units that exhibit the problem, although judging by some anecdotal reports, whole shelves of iPods at some stores have this problem. Fortunately, it appears as if it’s possible to notice the issue with the nano inside the box. Nearly all customers say, that they wouldn’t notice this tilt, if the didn’t know about it.
Take a look around bying your new Nano.