AirPrint was supposed to be as revolutionary as AirPlay, allowing wireless printing to shared printers on a network. That part of the functionality appears to have been pulled at the last minute; multiple sources confirm that AirPrint does not function as was advertised a couple months back, even after applying the 10.6.5 update. Wireless printers with AirPrint functions built-in reportedly do work, but hardly any of those printers have been released yet. Hopefully Apple will sort out its AirPrint problems in a forthcoming update, because as it stands now, AirPrint functions fall far short of what we were promised.
Find in Page in Safari
A long-awaited feature: similar to "find in page" functionality on the Mac and iPad, you can now search for text on a page in Mobile Safari. The feature is in a somewhat odd place -- the search field (the one that most of you probably have set to "Google"). Beneath all the search engine results for your search term, you'll find how many results, if any, are present on the currently loaded page.
Enter search term in the bar, and it'll be highlighted on the page. Makes life easier.
Volume slider in multitasking bar
This is one of a few areas where the iPad got some extra functionality that iPhone users miss out on. On the iPad, swiping left twice on the multitasking bar will give you controls for volume, AirPlay, and brightness. On the iPhone, you don't get brightness controls. Personally, I'd have been happier with a brightness slider rather than a volume slider -- there's buttons for volume, after all, unless you...
Disable volume changes
If you've always wanted to prevent your ringer and alert volumes from changing via the hardware buttons, you're in luck. As the above screenshot shows, you can go into Settings > Sounds and disable the iPhone's ability to change the ringer/alert volume via their dedicated buttons. You can still change volume in games and apps using those buttons, but they'll no longer affect the volume of ringtones, text alerts, or various other system sounds. If you find yourself pressing those buttons accidentally all the time, this setting seems tailor-made for you.
There are three changes to Messages (and, since this app doesn't exist on the iPod touch, this is one section owners of that device can safely skip over). First, there's now a FaceTime button located at the top of a message thread, making it easier to initiate video calls with your contacts.
Second, Apple has introduced 17 new text alert sounds. Unfortunately, to be blunt, they're all terrible. Not only are the sounds themselves incredibly irritating for the most part, almost all of them are far too lengthy for a text tone. The length of some tones is even pushing the envelope for a ringtone. Feel free to check these tones out and see if any of them strike your fancy, but for me, I'm sticking with the tried-and-true "Tri-tone" -- along with just about every other iPhone owner I know, unfortunately. Maybe someday Apple will decide to let us use our own custom tones for text alerts, but sadly, that day has yet to arrive.
In the meantime, the third new feature of Messages is probably the most useful: you can now assign individual text tones to each contact, the same way you can for ringtones. So if you want to use Tri-tone for everything except your boss, you can.
Apple made some other, more minor changes to iOS 4.2. The built-in Notes app allows you to change fonts to something other than Marker Felt, which is nice for the five or six people using Notes instead of a superior app. The icon for the Voice Memos app has changed, and not for the better -- it sticks out like a sore thumb and gives us yet another blue app icon. You can place more restrictions on iPhone functions, like preventing app deletion, changes in Location Services or e-mail accounts, and disabling Game Center friend requests.
It wouldn't be a big update without big bugs to go with it, would it? Several users who installed the iOS 4.2 gold master, myself included, have noted rather flaky performance over WiFi. Mobile Safari and other data-loading apps like Twitter or Facebook will sometimes randomly fail to connect -- they don't time out, they just immediately throw up an error saying "The page could not be found" or something similarly unhelpful. Performance over 3G or GPRS (and presumably EDGE) is fine; the problem exists only over WiFi. Various online forums have given suggested fixes, and all the usual suspects are there: reset network settings, restart the phone, restore iOS, and so forth. None of these fixes have provided a permanent solution, however.
Note also that this is a fairly intermittent issue; I was plagued with connection issues over WiFi earlier this week, but I haven't had any problems at all in a couple of days. I haven't noticed any other bugs in iOS 4.2 yet, but there are probably at least one or two others lurking around in there somewhere.
iOS 4.2 is nowhere near as groundbreaking on the iPhone as it is on the iPad. The OS update transforms the iPad into almost an entirely new class of device thanks to multitasking support. The only real groundbreaking new feature for the iPhone is AirPlay, but it's one of those features that, once you use it, you wonder why the iPhone wasn't able to do it all along.