Android 4.2 is now available, in the sense that new Android releases are usually "available." That is, 4.2 is available to those who bought brand-new, Google-derived Nexus devices, such as the very sold-out Nexus 4 or the Nexus 10 tablet, those willing to manually install the 4.2 ROM on their Nexus 7 or GSM Galaxy Nexus, and those with the ability to compile their own build from source code.
I am in the middle, having flashed a factory image of Android 4.2 onto my Nexus 7 (Wi-Fi, 8 GB storage) yesterday. Here are some impressions, evenly split for no particular reason.
Multiple user accounts: convenient, but slow to load
All tablets are meant to be casual, pick-up-to-look-up devices. You want to pass them off in the living room, share them on a trip, let your friends check their email. But most tablets are locked into a single user account, for the primary owner's presumed convenience. Android 4.2 offers tablet owners additional user accounts (tied to Google accounts) to make sharing easier.
Easier, sure, but fairly slow to switch over on a quad-core device, at least when starting up the device. And since the device boots up to the primary owner's account, it can be a while before both accounts are up and running smoothly. And the owner has to watch their space usage a bit more closely from there on out.
New notification/settings "shades": somewhat unexpected
Android was trendsetting in its notification "shade," which one pulled down with a finger from the top of the screen, revealing everything your phone and its apps wanted to tell you about. Ever since the first Android phone went on sale, you would drag your finger from the top, and a single, centered shade would come down with it.
In Android 4.2, at least on a tablet, there are now two shades. A shade on the left has your notifications, while a shade on the right shows quick settings. If you are used to casually, somewhat haphazardly flicking your finger from somewhere close to the top-center of the screen, you might not get what you were looking for. The Nexus 7 seems to give the left notification edge a bit more room, which makes sense. But it may take a while to get used to the two shades, and for the right settings shade to be useful for longtime users.
Google Now: many more handy reminders, way more settings
I dig Google Now, even if it takes some thinking and testing to figure out exactly what it is. But that's also what I like about it: it works in just some kind of magic way, because Google knows you all too well. If you're good with your privacy and Google's knowledge of you, it's quite nice.
In Android 4.2, Google Now has many more abilities, including the ability to search through your Gmail for reservations, shipments, and confirmations. And it can bring up driving directions and other details of things you've searched for. But setting them up to work just right now involves digging through many, many settings, and also enabling some history-sharing settings on the Google account side. That feels less like management and more like an unpaid personal IT administration gig.
Google Voice is currently broken in Android 4.2 Update: Fixed, same day
I've read the early reports of Google Voice's bustedness, and tested it myself, and, yep, Google Voice is seriously broken. The best work-around right now is to use Voice's web site, which seems to have discarded its minimalist mobile version, or to use a third-party app to access Voice.
Nothing is good about Voice being very broken on Android 4.2, although it's one app update away from being fixed (Update: And that update did arrive, later the same day as the release). My one scant hope is that someone high up at Google will notice that Voice is quite often in this situation of being a secondary, easily forgotten service, and make a call to start treating it right and tying it more deeply to Android's future.
The lock screen does a lot more, and is quite wonky
My Android compatriot JR Raphael did the yeoman's work of detailing every swipe, gesture, tap, and widget you can add to the Android 4.2 lock screen. I can't add much on specifics, except to say that it all feels a bit overstuffed.
And if you choose to lock your device with a code or number, all those new things you can do feel like something of a tease, because you still have to unlock your device in the usual fashion, regardless of which way you swipe. iOS has a handy feature in which you can activate just the camera from the lock screen, without having access to anything, not even old pictures. I'd love to see Android pick that up.
Edit: I misunderstood how the lock screen widgets work in Android 4.2, especially with a locked phone, possibly due to my regular use of a third-party unlocking tool. You can, in fact, activate the camera and at least browse your lock screen widgets from a PIN/gesture/pass-locked phone, though accessing them at a deeper level requires an unlocking. I am still not quite impressed with the feeling of it all, especially the tiny sphere that now serves to unlock Google Now from the lock screen.
What Android 4.2 features do I have the wrong take on? Which give you a similarly good-with-the-bad feeling?