I installed LJ7 (stock + rooted, via Odin) yesterday. It froze twice while I was setting it up. Then it froze again later when I was just using it. By "froze", I mean just that. The UI just stops responding. I can pull down the notification window after it freezes, but then it stays stuck on that screen. Turning the screen off then back on again gives me the same screen (i.e. no lock screen). None of the buttons work (Home, back, menu, long-press Home). Even holding the power button doesn't give the menu to shutdown/restart. I wiped it and went back to cm10.
btw, my battery seems worse now, even back on cm10, so I think the updated radio must be drawing more power.