I have to say that so far I'm impressed. It is noticeably faster than IE. I'm a total speed demon when it comes to computing. I use keyboard shortcuts to minimize trips to the mouse. I disable services that aren't necessary to minimize boot time. I've even gone so far as to prune the directories that Windows Search indexes to minimize its impact on responsiveness. I really *really* hate having to wait on my PC for any sort of routine operation.
The UI is also refreshingly clean (though I did struggle a little bit looking for the "Home" button - just added my homepage as a link). Immediately after installing it I noticed more screenspace devoted to the web page - no status bar at the bottom of the page, no file menu at the top and the favorites/bookmarks section isn't in the floating toolbar style. Not using the floating toolbar frees up a little vertical space taken up by toolbar borders. It's just a cleaner UI.
So far so good. They've definitely met their goal of getting the browser out of the way.