The iPhone 3GS has been an undeniable marketplace hit since its release on June 19, and will likely continue to soar in sales despite three customer complaints that have surfaced recently. The big three gripes: the iPhone 3GS battery life is dismal, the 3GS overheats, and there's a serious SMS vulnerability.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\u2014about 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\u2014that is, alerts\u2014when 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\u2014so 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\u2014guidelines that did little to put out the fire.One of Apple's tips: "iPhone 3G and iPhone 3GS should be used in environments where temperatures remain between 32 degrees and 95 degrees Fahrenheit. Temperatures outside of this range could decrease battery life temporarily or effect performance." Here's another: "Avoid using data intensive applications, like GPS or streaming-media apps, for extended periods of time on hot days or while in direct sunlight."The most serious of the iPhone's problems concerns a new SMS vulnerability that could allow an attacker to remotely install and run unsigned software code with root access to the iPhone. Security expert Charlie Miller, who hacked a Mac via Safari in 10 seconds at this year's PWN2Own contest, said in a presentation that the weakness is in the way iPhones handle text messages.The seriousness of this problem has spurred Apple's intent; Apple is reportedly working on a patch that should be available later this month. "I believe that the SMS vulnerability may be the most pressing, since stories of hijacked, zombie, misbehaving iPhones are more likely to leave a long-lasting negative impression than are the heat and battery life issues," says Forrester analyst Charles Golvin.But is the vulnerability an Apple or AT&T problem? Does it affect other manufacturers? Apple's lack of formal releases and documentation frustrates analysts like Dulaney. For instance, Apple said the iPhone OS 3.0 SDK released earlier this year has hundreds of new features - "but you can't really find them," Dulaney says.Dulaney also points to Apple's lackluster documentation practices with the iPhone 3GS hardware-based encryption. "You can't find out how the encryption is done," he says. "For those who know encryption, it's not a simple word. It's about how it's implemented."Are you running into iPhone problems? Send me an email at email@example.com. Or follow me on Twitter @kaneshige. Follow everything from CIO.com on Twitter @CIOonline.