All new! All different! But you can’t buy it yet.Windows Mobile is dead. Long live “Windows Phone 7 Series,” which kills Microsoft’s old, unloved WinMo at version 6.5. Announced today at the Mobile World Congress in Barcelona, the renamed and redesigned mobile OS is expected to reach the market this holiday season, in the fourth quarter. It also represents a late–and possibly too late–effort by the world’s largest software company to catch up with the iPhone, Android, BlackBerry, and others in the fast-growing smartphone market. (Nationally, MSFT has about 18 percent of the market and just under 9 percent internationally, lagging behind Apple, Nokia, BlackBerry/Symbian.)CEO Steve Ballmer introduced the new software in a presentation. And the initial response is favorable. You can’t call the following impressions reviews, since the OS–and new handsets designed for it–aren’t yet available for hands-on demo. But as MSFT attempts to claw back market share in mobile OS, here’s what some tech observers are saying about WinPho.”A rare moment when Microsoft scrapped previous versions of its software in favor of building something new from scratch.” New York Times”A total break from the past. Windows Mobile isn’t just dead, the body’s been dumped, buried and paved over by a rainbow brick road.” GizmodoBut where are Walter Mossberg and David Pogue, the Siskel and Ebert of tech reviewers? We’ll link to their impressions when they’re up.