I recently upgraded my tablet to ICS (Android 4.0). I have found one small bug. When I am in Read mode, and I tap on the screen to view the menu frames (or whatever they are called) that come down from the top and up from the bottom, the menu buttons have white horizontal streaks going all the way across them, and that makes the buttons hard to make out or read.
I'm running (CM9) ICS on my HP TouchPad and have not seen this yet, but on my Droid Incredible 2 running (CM7) Gingerbread I have the same problem.
Same problem here running CM9 ICS on Nook Color.