Historically, Apple does a poor job of sharing details about its technology and is sometimes slow to respond when such complaints arise or Apple's response falls short of expectations, analysts say. "Apple needs to get better at this so that buyers can understand what the limitations are upfront," says Gartner analyst Ken Dulaney. "This is why Apple and the enterprise have a somewhat rocky relationship."

[ Apple offers tips on how to prevent the iPhone from overheating, reports CIO. | Apple plans to patch a serious SMS vulnerability on the iPhone. ]

The biggest complaint concerns a short battery life, which is ironic since Apple touted improvements of the iPhone 3GS battery at its Worldwide Developers Conference last month. Among those claims, Apple said the iPhone 3GS would deliver 9 hours of use on Wi-Fi, 10 hours of video playback and 30 hours of music on a single charge—about a 30 percent upgrade to the iPhone 3G. Indeed, the iPhone 3GS battery is physically a little bigger than the one in the iPhone 3G.

More than a few users, however, have reported that the iPhone 3GS drains the battery quickly. The problem may be that the software isn't managing power efficiently, analysts speculate. For instance, iPhone OS 3.0 supports push notification—that is, alerts—when apps aren't running. The iPhone constantly buzzes during an instant message chat even if you're on the computer and not the iPhone. This could be draining the battery if the software isn't handling push features properly. If so, the problem won't be fixed until the next OS update.

Apple's response? An Apple spokeswoman told the LA Times that battery life is highly dependent on usage—so if you don't change your usage pattern from the old iPhone 3G, then performance shouldn't change either. It was a lukewarm response to a potentially serious problem, analysts say. "The battery is the first concern because it could be potentially dangerous," Dulaney says, "and we have no clue, except for some dos and don'ts, why it's happening."

Last week, some iPhone 3GS users also began noticing that their cool new devices were overheating: Some units with the white casings turned burnt-brown. Other issues surfaced, such as rattling noises and high-pitch sound emissions. Apple responded by issuing a set of simple guidelines to prevent overheating—guidelines that did little to put out the fire.