Apple’s fourth-generation iPod Nano returns to the original long, light, and slender formula that put the series on the map. Offered in an attractive range of nine colors for both the 8GB iPod Nano ($149) and 16GB iPod Nano ($199) models, Apple has yet again raised the MP3 player bar.

Design

The Nano 4G feels impossibly light and thin, with a seamless metal construction that prevents it from snapping like a twig. A slightly curved design gives the Nano 4G the essence of an airplane wing, repeating the rounded design themes of Apple’s iPhone 3G and second-generation iPod Touch. Compared with the short, squarish design of last year’s Nano, the long, tapered body of the fourth-generation Nano is more comfortable to grasp.

Curved glass now covers the iPod Nano’s screen, giving it better resilience against scratches–in theory. The curve of the glass screen lies flush with the slight curve of the Nano’s body, and although the glass is inherently glossy and reflective, we didn’t notice a diminished viewing quality compared with last year’s Nano.

The shape may have softened, but the dimensions of the fourth-generation Nano are nearly identical to the second-generation version, measuring 3.5 inches tall by 1.6 inches wide by 0.25 inch…