Microsoft is counting on its alliance with Nokia, still the world's biggest handset maker, to rejuvenate its flatlining Windows Phone franchise. The Lumia 710, the partnership's first entry in the U.S. market, is a slick little 8-GB smartphone that hits stores Jan. 11. But on its own, it won't be enough to jack up Windows Phone's market share--just 1.5% according to Gartner--all that much.

The problem: Despite some unique features, like having the Nokia Drive auto GPS system preinstalled, the Lumia 710 is still just another Windows Phone. That's not Nokia's fault--Microsoft pretty much laid down the law to hardware OEMs when it came to Windows Phone design, specs, and the software interface.

The latter is key. I personally find Windows Phone's Metro interface and Live Tiles attractive and easy to use, but the fact is it hasn't caught on with consumers. Many have been conditioned by the Apple iPhone's success to believe that a smartphone has to have icons, or it just isn't a smartphone.

Nokia Lumia 710

That's why Microsoft's decision to opt for an entirely new interface design, while daring, was a big bet--one that it so far isn't winning.

But if you do like the Windows Phone paradigm, you won't be disappointed with the Lumia 710, which sells for $50 with a contract from T-Mobile. It's got everything you would expect to find on the latest batch of mid-market Windows Phone 7 entries, which also includes the Samsung Focus Flash and the HTC Radar.

Windows Phone 7.5 Mango preinstalled? Check. A 5-MP camera with HD video recording? Check. 1.4-GHz Qualcomm Snapdragon processor? Check. Access to Microsoft mobile exclusives like Office, Xbox Live, and Local Scout search? Check, check, and check.

One differentiator I liked is the fact that, unlike on other Windows Phones I've tried, the main navigation bar beneath the display uses physical keys. Call me a sucker for tactile feedback. What I didn't like is that the side buttons, for power, volume, and camera, are virtually flush to the casing. This was particular irksome when trying to depress the camera button for a quick pic.

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But overall, the Lumia 710, available in black or white, is a solid entry in the Windows Phone market and should appeal to those with a brand preference for Nokia and/or T-Mobile.

The real litmus test for Microsoft's decision to ally with Nokia, and possibly buy the company outright, will come when the phone maker introduces the N9-inspired Lumia 800 to the U.S.

Nokia's current flagship Windows Phone, which is already available in Europe and can be purchased unlocked on Amazon for $550, sports Carl Zeiss optics in its 8-MP camera, a curved AMOLED touchscreen, and sleek unibody construction. Nokia has yet to set a date for the Lumia 800's U.S. arrival.

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