I just unlocked an iP5 yesterday and had to do the restore to get it to unlock. Got the congratulations message.
My email from AT&T said to wait at least 24 hours to do the unlock, which I did. Did you wait or just try it after receiving the email?
Did you select "Restore iPhone..."? Then, it should display the congratulation message.
Did you select "Restore iPhone..."? Then, it should display the congratulation message.
I had the same issue when I tried to unlock two of my iphone 5 last week.
the trick to get the unlock message from itune is that you need to reset "erase all content and settings" before you restore it.
if you forgot to reset, you can still reset it after restoring it. then plug it back in and itune willl show you the message.