I'm just now getting around to using Android 4.2. I find a lot of times initial releases of new Android versions are plagued with bugs or my third party programs haven't caught up with the new version yet. So typically I wait a little while till things stabilize a bit. Now that I am on 4.2, I figured I'd ramble off a few thoughts here and there about the new additions to the OS.
First off, "Daydreams". Let's be realistic here: it's a fancy name for a screensaver. Of course there's nothing wrong with screensavers, but on a phone or even a tablet in which the screen is typically turned off most of the time, a screensaver seems a bit pointless. Still, it's a nice feature. You have choices between a shifting color effect, a clock, and two types of picture displays (my rooted ROM also includes the Jelly Bean easter egg as a choice as well). All of the choices have variable options.
Secondly, notification toggles. Rooted users and those with certain skins already have had these for a while, but this is the first time it comes to stock Android. Overall the implementation is good. The tiles are nice and large give you a good selection of options (my custom ROM gives an even larger selection). I think this is likely the most useful and important of the additions to the OS.
Next, lockscreen widgets. I'll admit, the way they choose to do this threw me for a bit of a loop. Instead of just doing it like you would on a normal homescreen, they choose to basically have you create panels for each individual widget. On the right, you have your camera from the lockscreen option and the widget are on the main lockscreen and any to the left. One thing that irked me was the fact that you have to pull down on the widget or else the unlock controls are in the way. Otherwise, it's a good addition. However, the choices of widgets are limited to certain basic functions and Google apps (my ROM allows for any widgets).
Now, onto keyboard enhancements and photosphere. The biggest thing for the keyboard is a Swype-like style addition. For those who don't have Swype or use it, it allows you to draw lines over the letters to create the word instead of manually punching it in. It's a pretty good implementation, but it has a few drawbacks. Mainly the keyboard isn't very adaptive and requires you to move slowly in order to be assured you inputted the correct word. It also forces you to manually add new words in settings section with the languages as opposed to on the fly like Swype does. Overall, it's a pretty good first effort.
Photosphere is completely gimmicky. Basically, it's like a sphere version of panorama mode. However, the cool effect is that after you take the photo you can push a button in corner of the screen and pan and scroll around the photo you just took . In effect, you create a virtual appearance to it. Problem is it requires 4.2 to take advantage of this feature so sharing with someone on earlier versions is pointless. Secondly, I just can't find that much use for it.
Finally, there are a few misc. additions like support for wireless displays, multiple user accounts (only tablets or custom phone ROMs can access this), SELinux (which apparently existed for 10 years, but Google just now decides security is important), a new clock app, and a few other things not worth mentioning.
Overall, I think 4.2 is mostly fluff. There aren't any groundbreaking features or performance enhancements. Most of the things added I already had in one form or another such as Swype or notification toggles on earlier custom builds of Android. Basically, this is closer to Gingerbread than it is Froyo. Most aesthetic rather than functional.