I'm running it right now. I downloaded the "Activated" firmware (even though I'm an ATT customer). It installed without issue. I could deal without the replacement boot screen that's pimping a site called "ven000m", and it makes me wonder just what other changes they've made to the OS. As with any new software, some of the apps (third party) are a little shaky, but I'm sure those will be ironed out in the near future. I'm still trying to figure out the additional features for OS4, like the folders and books. So far I haven't had much luck on that front.
I'll report back with any issues that I may encounter.
Thanks to everyone for a great site.