The rapid adoption of Apple's iOS 6 has been impressive. Initial estimates claim that as many as 25 to 35-percent of all iPhones were running iOS 6 within 48 hours of its release.
With all those users hammering away at the new OS, you can be sure that any bugs that survived Apple's beta testing would soon be uncovered and publicized on the web. And that's exactly what's happened.
[ FREE DOWNLOAD: The Apple security survival guide ]
An excellent first stop to check for bug reports is the iOS section of Apple Support Communities. Two hardware-related items there especially caught my attention: short battery life and loss of Wi-Fi connectivity. Other iOS 6 problems, beginning with iTunes Match, extend beyond what I found at Apple's forums."
Short battery life
A significant contingent of iPhone users report that their iPhone's battery depletes unusually fast under iOS 6. While the majority of postings are from people moving up from an older iPhone to an iPhone 5, the symptom also appears to affect those upgrading to iOS 6 on an iPhone 4 or 4S. It's still not clear what percentage of iPhone users have this problem; it's certainly not a majority or we would be hearing a lot more about it.
If you are among the unlucky ones bothered by this rapid depletion, the most often suggested fix is to launch the Settings app and navigate to General -> Reset. From here tap, Reset All Settings. After doing this, you'll have to re-enter several custom settings, but the battery issue should hopefully be resolved.
I say "hopefully" because, as is always the case in these matters, there is no single fix that works for everybody. A sudden rapid depletion of the battery charge can happen to any iPhone user at any time. For example, about a month ago, my iPhone 4S running iOS 5 developed "short battery life syndrome." When it happened, my first step was to check for apps that are known to drain the battery even when they are not the active app. A primary suspect is a GPS navigation app that continues to track a route. I called up the multitasking bar and force quit about a half dozen potential culprits. To be extra safe, I launched Settings and disabled Location Services. None of this had any effect.
In the end, at the suggestion of an Apple Store Genius, I killed every app listed in the multitasking bar. This took awhile, as several dozen apps were in the bar. But it worked. Battery life immediately returned to normal. Even though my multitask bar is once again filled with apps, the symptom has not returned. So I'm guessing it was an intermittent bug in some still-unidentified app.
Wi-Fi connectivity loss
Several Apple Support Communities threads cite a loss of Wi-Fi connectivity in iOS 6. In a massive thread titled iOS 6 WiFI Disabled, users report that the Wi-Fi option on their phone is grayed out and unselectable. Another Apple Communities thread covers a related Wi-Fi problem specific to the iPhone 5: "My iPhone 5 connects to Wi-Fi networks and remembers them, but receives absolutely zero data through the network. LTE and 3G no problem."
Numerous potential solutions are offered but there doesn't seem to be any that are universally supported. Some were able to restore their Wi-Fi access only by downgrading back to iOS 5 (which is not even possible for most users at this point). The good news is that, despite the large number of reports, most users are not having this symptom.
A footnote: Some Wi-Fi losses may stem from a problematic interaction between Wi-Fi and cellular data connections. Numerous users have found that turning off Cellular Data in Settings gets their Wi-Fi working again. Others report that data is being routed through the iPhone's cellular connection even when the device is on a Wi-Fi network. According to one theory (which I cannot confirm as accurate), this all may be a consequence of a feature, intended to be added in iOS 6, that appears to have been dropped at the last minute: Wi-Fi Plus Cellular. The problems could occur because the feature remains erroneously enabled in some iPhone 5 units or on the phones of developers who were running beta versions of iOS 6. If so, it will almost certainly require an update from Apple to fix this.
After upgrading to iOS 6, some users found that the music in the Music app was gone. This appears to happen only if iTunes Match is enabled. The precise symptom is either that music remains listed but unplayable, with all songs having a posted length of 0:00--or there is a lone Music screen that says "No Data."