If you want to get into the real differences between Atom and RSS, just go to Mark Pilgrim's new article for XML.COM.
This is the best article I've seen to explain what the controversy is all about. Not from a political view, but a programmer's view. An example:
The other problem is that there is no way to know whether an entry's description is being used as a summary or as full content. Atom solves this problem by simply defining separate summary and content elements, and Atom feeds generally contain one or the other (although mine includes both, which is also valid).