I also Upgraded to ICS on the initial release.
I seem to have had many similar issues.
-Internet is super slow now
-Battery life is terrible
-No longer have a scrolling wallpaper, and no longer adjust to screen position
I have done several things to fix. I constantly am clearing the ram, as it seems to run high. I have done a master reset. After which, many contacts upon restore became miss-matched. Some disappeared all together.
My phone has not been rooted/unlocked/jailbroken, etc.