Just an FYI - When I upgraded to ICS, voicemail was removed from my account. I just got through yelling at AT&T. They had no explanation as to why it was removed. I had some voicemails that I would have liked to keep but it wasn't that big a deal (and I got a $25 credit). For others it may be a bigger deal.
Everything went perfectly with the upgrade - no errors, or warnings and I like ICS so far.
Everything went perfectly with the upgrade - no errors, or warnings and I like ICS so far.