The hardward:
No one will have any trouble recognizing the new device from its face -- it's essentially identical to the original iPhone. Thankfully, the bright, high quality, high resolution 480 x 320 3.5-inch display that's just so easy to love, hasn't been changed a bit. Unfortunately, it's still every bit as much a magnet for smudges and fingerprints -- in fact, even more so now that the rear of the device has dropped its chic matte aluminum in favor of black (or white, optional on the 16GB model) plastic. Hey, at least now it's more symmetrical.
The move to plastic seemed almost inevitable now that the iPhone has so many radios, frequencies, and antenna needs (GSM, EDGE, HSDPA, WiFi, Bluetooth, GPS), but while we do prefer the original aluminum, the plastic does feel pretty solid and not at all flimsy, which is more than we can say for a hell of a lot of handsets. There's no doubt about the fact that we'd have preferred a matte or soft-touch finish to the glossy plastic, but that's all a matter of taste.

The software
Anyone that's used the original iPhone knows what a delight the device can be to use -- except when using the old mail app -- but the hardware is only one part of that. An accurate capacitive touchscreen and well optimized mobile processors form the basis of that experience, but the iPhone continues to derives its real power in usability. The iPhone 3G and the second release of mobile OS X have given the device numerous useful new features while keeping in line with expectations that they not slow down the experience, nor overwhelm new or experienced users. So far, so good.

VIA: EngadgetMobile.com