I like it. Updated (from 4.0.2 I believe) via Kies on a slow-*** PC with Windows XP and it actually worked! Never got the OTA message, but I go through an ATT reseller, so that may be the reason. Overall it seems my phone (I777) is running a bit faster/more smoothly, but there is something majorly farked up with the Play Store. Getting "Insufficient Storage" every time I want to update an app. But that's for another thread.
As for battery life... I dunno. I have an aftermarket extended battery (3200 mAh or something like that) so I get 10-12 or so hours out of a charge under fairly heavy use. After I updated, I let the battery drain completely, charge completely and then I think I got about 13+ hours
I like that I was able to drag and drop the icon to use Chrome as my default browser, instead of having to go through a bunch of steps in the Settings. I *really* like the new Calendar layout. The look and feel is more like the one hanging on your wall and in the Month View you can see the names of your Events. What I don't like about the new Calendar is when you're in Month View, it shows Events for "today" at the bottom and you can scroll up and down, but it is a very small space and a bit hard to read even on the (Super?)AMOLED S2 screen. It would be nice if you could flick the Month View up with your finger to reveal the Day View and vice versa.
Supposedly the camera is better. I don't care, I use Vignette and it's far superior. I hope the issue with the video recording is fixed. I get bee-you-tee-ful HD video, but after about 5-10 minutes or so, the audio craps out. It starts to kind of stutter and then goes scratchy. I haven't tested yet, but I'm hoping this has been fixed.
Overall I really like the update, though I will probably root my phone and install either SlimBean or ShoStock3 (basically I want a stripped down version of 4.2.x so I can install just the apps *I* want and nothing more - so my phone runs smooth like a freakin' fighter jet.) But this will work for now. It will more than work. I'm gonna stick the stock battery back in, let it charge fully and get back to you on battery life.
A little off-topic, but I love the S2. Like, LOVE love it. But being 2+ years old, I fear it will be time to upgrade soon (read: phone goes to the wife and *I* get an upgrade.) I'm looking at th SIII (I747) as the next logical step up, but I've heard complaints about the single "do all" button. But in theory, it shouldn't matter with 4.2.2 right?