I just mustered the courage to try, and did put the new OS on my skyrocket.
I did not even try it on my 64 Bit Win7 machine after reading about the problems. I also figured I did NOT want that Keis thing on my "real" computer if it's like I-Tunes. Worse than a virus IMO.
Anyhow, I used a small Samsung netbook (Win7, but the starter edition) that we have. It doesn't have the minimum recommended processor, so I knew it'd be slow.
And it WAS slow.
Starting with the downloading of the Keis program from Samsung's site at dial-up speeds (It took about 45 minutes to DL 88 meg). Then, I installed the Keis onto the little laptop, and that took about 45 minutes, too. It kept flashing a progress bar saying it was installing the same thing over and over and over. I'm serious when I say that it showed that progress bar and same message about 50 or 100 times. I gave up on it, actually, and tried to cancel out of the installer, but it seemed locked up and stuck in that loop. But oddly, it eventually did seem to successfully install just before I tried killing it with task manager. Very odd!
I removed the micro SD card, then connected the phone. I did use the "factory" USB cable and it detected the phone. But it had to load the USB drivers for the phone (of course) before it could recognize it. But it did that successfully, too.
I then did the backup using Kies. The first attempt at that, things locked up. I managed to kill that, and then simply restarted the backup. The second time, it acted like it was actually making progress, and seemed to be going smoothly until very near the end when it again appeared to freeze.
I waited a long time, and then tried to cancel again. But as with the installation of Keis, after I'd clicked the cancel button, and seemingly got no response, it suddenly said that it had completed the backup.
At that point, I went ahead and had it do the OS update. That took a while, but at least it made steady progress and that whole operation seemed to go smoothly. Of course, it didn't follow what the instructions said it would do, but it was relatively painless.
All in all, it took over 2 hours to get the job done. But I was watching a stupid movie and a couple of mindless shows on TV, for what that's worth.
I didn't lose any data, contacts, or apps. Everything is still there. I did have to reorganize the layouts of the app icons, but that was expected.
I haven't been running it long enough to say what all will be different, but so far I've found a few small new features that are nice. Like being able to have it show the percentage "full" of the battery on both the main notification bar and on the "locked" screen.
It also shows the setting for the next clock alarm on the locked screen.
I did have to get rid of some of AT&T's bloatware icons scattered here and there. And there appear to be a few new apps that I almost certainly will avoid, but which AT&T have thoughtfully provided.