Adobe is already the king of Flash content, mainly in web advertisement form. As its tools are moving to the web platform (Adobe got tired of having its software pirated), they are complementing their suite with more content creation tools, Story being the latest one.
Adobe Story is NOT a replacement for Final Draft (and equivalents) although it shares many of the core features of a good script authoring package (formatting being the top-most). Think of Adobe Story as a tool to make Flash banner ads, vlogs or similar small videos people put up on Youtube. That's the intended market segment, not Hollywood movie scriptwriters.
You can't go wrong with Final Draft, Movie Draft, FadeIn Pro, Celtx, etc. Those are the tools of the trade.
-cb