Yes, I have u/g my 8GB iPod Touch 4G to OS 5.0.1, and what an ordeal! MAKE A LIST OF ALL YOUR APPS BEFORE YOU DO THIS! Maybe it was the synch in iTunes afterward, I'm not realy sure. Something removed about 60 of my approximately 75 apps! Luckily, I found the list of my d/l apps at the App Store. From there, I was able to restore (d/l and re-install) each one, slowly, one-by-one. I hit a little cloud icon next to each app in the list to restore them. They were all free apps, so I'm not sure if I would have had to pay again for any paid apps. Probably so?! Once I installed things like the Kindle app and iBooks, it automatically restored the ebooks that I had in each one. Other apps' personal settings and data were fully restored. Maybe having iCloud enabled helped out with this restore? I did have to log into most all the apps and services all over again. What a hassle! As far as overall system speed. It seems to sometimes hesitate a bit at start-up after it's been sleeping, and also sometimes at the first use of an app. But it seems to catch up with itself rather quickly, so this really doesn't create a permanent issue. It's done this since it was brand new. No worse or better with the new OSs. As far as battery life, it sure seems to not be draining near as quickly as it was since the original IOS 5 upgrade, which was about 2 weeks ago. My first impression is that the OS u/g is worth it, but beware of mass app loss!