So are 300-plus new features worth $158? That answer will vary, because no single user will ever take advantage of all -- or maybe even half -- of those 300 features. But given the impressive value of Time Machine and improvements to existing programs such as iCal, iChat, Mail, and the Finder, most active Mac users will find more than enough reasons to consider that upgrade cost money well spent. Despite a few interface missteps, particularly when it comes to the menu bar and the Dock, Leopard is an upgrade that roars.