According to CNet:
Downside: Getting used to the new layout may be hard for die-hard fans of Hotmail. Kahuna works with Internet Explorer 5.5 and up, but not with Firefox….
I’m a bit concerned about that, and wonder what Microsoft’s plans are regarding Firefox and other non-IE browsers. Will they be stuck with the old interface and begged to upgrade? Will future beta’s of the new layout be fixed so they work with other browsers? It’s clearly possible as Google has done it.
If anyone at Microsoft wants to clarify the plans for other browsers, I’d of course welcome that dialog.