The article is called: The Big Picture - Upgrading to Release 12.1. I co-authored this with Mike Swing from TruTek. You have to be an Oracle Applications User Group member to get to the article, so if you're not and you're just dying to know what the big picture is, you can download my presentation on it. The article is prettier than my presentation, though. For a more detailed version of the topic, check out Mike Swing's paper The Big Picture - The Release 12.1.3 Upgrade Review.