First, before you consider switching, realize that Chrome is very much a beta release on the Mac. As , Chrome for Mac is missing many features found on its more-advanced Windows counterpart, including major items such as a bookmarks manager and support for , along with less-obvious features like multi-touch gesture support, 64-bit compatibility, and support for and standalone browser applications, like those you can create using .
Beneath these stated omissions, digging into Chrome's preferences reveals additional not-quite-there-yet features. You can't view your cookies (though you can change your cookie acceptance settings), change auto-opening settings, change fonts and language defaults, or manage your SSL certificates. All of these things are coming, but they didn't make it in time for the beta.
There's also a grayed-out button for importing settings for other browsers, so you might think that's not functional, either. This feature actually works; you just have to access it through the Chrome -> Import Settings and Bookmarks menu item, not through the button in Chrome's preferences. At present, Chrome can import history and bookmarks from Safari; you can import the same from Firefox, plus cookies, saved passwords, and search engines.
So with all that's missing what there that might compel you to take a look at Chrome for Mac? The first thing I visually noticed is the tabs-on-top (almost) layout, along with just one input box, which Google calls the OmniBox.