Why? In a nutshell, it's fast - Really fast. But it is also using some of the newest web standards like HTML 5 which make web pages more like desktop programs. Chrome is a must if you use gmail or Google Docs. Plus it has great extensions which add functions without slowing things down or forcing you to restart your browser every time you install or update an extension.
Go ahead. Take my advice and try out Chrome, even if you have something better to do. And thanks.