With HTC and Nokia phones getting good reviews on build qualities, software instabilities aside, Apple has a lot of catching up to do with the second generation of its phone release dubbed iPhone 3G. The Cupertino, California company received high praises for the aluminum-backed first generation of iPhone but the 3G version switches from metal to plastic. With that comes some growing pains. Better reception was the outcome, but with it comes cracking plastics.

Users on Apple’s forum noted that the cracks occur mostly on the white iPhone 3G model (available in 16 GB capacity). It is unclear whether or not the black model (available in 8 and 16 GB capacities) has the same defect because the small, hairline fractures would be harder to see on the black. Users say that the crack, along with collecting dust, dirt, and other debris makes it more visible on the white plastic.

The photo from Engadget Mobile, reposted below, shows cracks either around the headphone jack, the silent switch and around the volume controls, and on the bottom near the synchronization port. However, users on Apple’s forums and other forums have noted cracks on the back surface throughout the device.

If you’re planning on upgrading or switching to an iPhone 3G, you should be wary of those issues. Since this isn’t a known material defect in the components, and Apple hasn’t acknowledged the problem, your mileage may vary in obtaining a replacement. Some users have been successful in getting replacements at the Genius Bar at Apple retail stores, while others have been less fortuitous in their efforts with Apple staff saying that it is only a “cosmetic” issue and there is nothing they can do about it.

It should also be noted that these phones, as reported in various forums, were not dropped or misused by their respective owners according to the owners’ reports.