Microsoft launched the latest version of its Windows Mobile OS on Tuesday, ushering in a new era of Windows phones. But reviewer reaction to the new smart phone platform has been more negative than expected, triggering worries that the company has another Windows Vista on its hands.

The problem is that Windows Mobile 6.5 doesn't go far enough to address the rapidly evolving competitive landscape, which is coalescing around multi-touch, Internet-savvy devices (e.g., the Apple iPhone) that are backed by vibrant mobile marketplaces. Windows Mobile 6.5 seems to hit all the high points—it supports touch controls, has an improved web browser, can connect to an online store, and is more consumer-friendly—but the new UIs appear to be tacked on to the aging Windows Mobile infrastructure, which reveals itself far too frequently.

Some Microsoft device partners (particularly HTC) overcome these problems by replacing huge chunks of Windows Mobile with their own UIs, often with mixed results. But although any attempt to improve Windows Mobile is appreciated, it's confusing that HTC and others appear to be innovating more on Microsoft's platform than Microsoft is.

At a special event in New York on Tuesday, Microsoft said that 30 or more Windows Mobile 6.5-based smart phone models would ship to users in more than 20 countries by the end of the year, and several are available in most major markets already. The devices include iPhone-like touchscreen phones as well as more traditional smart phones with fixed or slide-out hardware keyboards.

Microsoft says this diversity is key to the Windows phone ecosystem: Whereas Apple targets consumers almost exclusively with the iPhone, and Research in Motion's (RIM's) BlackBerry is used almost solely by business users, Microsoft hopes to straddle both segments with Windows Mobile.

That would be a good approach if it worked. But Windows Mobile seems about as consumer-friendly as RIM once you get past the thin veneer of UI that Microsoft added to Windows Mobile 6.5. And the company still has a lot of work to do to convince corporate customers that Windows Mobile is a more viable solution for on-the-go knowledge workers.

Meanwhile, the few remaining Windows phone enthusiasts are still looking to the future for salvation, this time in the form of Windows Mobile 7. Widely expected in 2010 for some reason, Windows Mobile 7 won't really ship until some indefinite time in the future, and Microsoft has provided absolutely no concrete details. In other words, at this point in time, Windows Mobile 7 is whatever you want it to be. And that's a lot, given the disappointing present.