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Nearly four years after Apple unveiled the iPhone, and more than two years after Google introduced its first Android smartphone, Microsoft is launching its effort to catch up. On Nov. 8, AT&T and T-Mobile will begin selling the first phones powered by the software maker's new Windows Phone 7 operating system

I've been testing two of these initial Windows Phone 7 phones, the Samsung Focus from AT&T and the HTC HD7 from T-Mobile; each will cost $200. Both are slender phones with large screens and virtual keyboards, though the Samsung is thinner and lighter than the HTC.

Microsoft has imposed tight requirements on the new Windows Phone 7 phones -- including fast processors, decent screens and adequate memory. However, in my testing this time, I didn't focus on the hardware. Instead, I bored in on the new Microsoft operating system, set to show up on nine phones this year, including some with physical keyboards.

My conclusion is that Microsoft has used its years in the smartphone wilderness to come up with a user interface that is novel and attractive, that stands out from the Apple and Google approaches, and that works pretty well. Instead of multiple screens filled with small app icons, or the occasional widget, Windows phones use large, dynamic tiles that can give you certain information, like your next appointment, at a glance. And it has special "hubs" for things like contacts and entertainment that use bold, attractive interfaces and offer personalized, updating information.

However, despite having all that time to study its rivals, Microsoft has inexplicably omitted from Windows Phone 7 key features now common, or becoming so, on competitive phones. These missing features include copy and paste, visual voicemail, multitasking of third-party apps, and the ability to do video calling and to use the phone to connect other devices to the Internet. The Android phones and the iPhone handle all these things today.

Plus, because it has waited so long to enter the super-smartphone market, Microsoft is starting way behind in the all-important category of available third-party apps. At launch next month, the company hopes to have about 1,000 apps available for the Windows Phone 7 platform, compared with nearly 100,000 for Android phones and around 300,000 for the iPhone. That means Windows phones will, by definition, be less versatile than their main competitors, at least at launch.

Read the full review at the Wall Street Journal.