It’s been a little while since I’ve taken Windows Phone for a spin. In fact, the last time Windows Phone and I were hanging out it was before the big Mango update. I had spent some serious with T-Mobile’s HTC HD7 and, overall, found the operating system to be fairly limited and without much in the way of developer support. Much has happened to the ecosystem since then, including the Mango update and the partnership with Nokia.Regardless of your thoughts on Microsoft or Nokia, we have two companies that were effectively pushed out of the mobile game by iOS and Android, working together to make a phone to try and win back some users. Their offering is called the Lumia 900 on AT&T’s 4G LTE network, and it’s a pretty big deal.Sweet, sweet hardwareNokia has always had hardware that stands out. Even back in the day when Nokia was cranking out 2G phones, you could spot them from a mile away. There’s no doubt in my mind that the Lumia 900 will differentiate itself from the crowd — in a sea of nearly identical slabs, this phone truly stands out. The polycarbonate monobody casing, available in both blue and black, create a surface that is just textured enough to allow your fingers to grip it, without adding a visual pattern to the finish. There’s no removable battery, making the casing a solid, seamless piece.Nokia’s ClearBlack glass lays on top of the body, almost like the polycarbonate shell is a removable case for the phone. The device is flat on the top and bottom, though the weight on the phone is ever so slightly imbalanced (due to the placement of the screen) so it doesn’t always want to stand up on its own.In a world of 720p screens and Retina displays, the Lumia 900 looks under-qualified to hang out with the big names in the smartphone world. The 4.3-inch 800×480 resolution on the Lumia seems like something we would have seen on phones over a year ago, and is sure to give smartphone power users reason to question the specs of the device. Despite the resolution, everything on this screen looks incredibly crisp and clear. The Windows Phone UI, with its basic colors and sharp shapes across a flat black background looks great. More than that, websites and text render very clearly. This display, underneath Nokia’s ClearBlack glass also shows up much better in direct sunlight than the Super AMOLED Plus display on the Samsung Galaxy Note or that on the iPhone 4S. The phone has an 8MP camera (with Carl Zeiss optics) in the back and a 1MP front facing cameraThe Lumia 900 is a 1.4Ghz single core processor phone with 512MB of RAM. In no way does this phone feel even remotely sluggish, no matter what I did to try and slow the phone down. The device performed exactly the same way no matter what, which is truly a testament to how Windows Phone is able to handle this hardware.The Lumia 900 has an 1830mAh battery inside, which is more than capable of keeping it alive for over a day on 3G. It’s not shocking that, compared to a dual-core phone with 1GB of RAM and a 720p display, you get better battery life. When connected to AT&T’s 4G LTE, the Lumia 900 will give you much closer to 14 hours of battery life. Compared to other 4G LTE devices the Lumia 900 gets great battery life, with the exception being the over-sized Galaxy Note.For more about the specifications, check out our comparison of the Lumia 900, the iPhone 4S, and the Galaxy Nexus.Mango is a huge improvement, but still fairly limitedIn the smartphone market, Microsoft’s Windows Phone is in a distant third place. The biggest downside to having a device in distant third is that, no matter how amazing the hardware is, there’s still not nearly as many apps for Windows Phone as there are for iOS and Android. Common apps like Dropbox are nowhere to be found, and the third party apps that try to offer access to the online storage locker don’t even come close. For users moving from Android, there’s no Google Apps, and for users moving from iOS, most of the popular apps you are used to are nowhere to be found. If you’re not bound to any particular set of services, moving to Windows Phone would be great, but I think those users are few and far between.My favorite parts of Windows Phone — the integration with Microsoft’s other services — are still around, which is great. The Xbox Live app, SkyDrive integration, and the Microsoft Office access are each really great tools that you can’t get anywhere else. For any user who is already enjoying these Microsoft products, the phone is a really pleasant way to complete that experience.The Mango update to Windows Phone brought a huge cache of new features, things like turn-by-turn navigation, multitasking, and more developer support for the LiveTile UI. These were, for the most part, a huge improvement to the Windows Phone user experience. Unfortunately, there’s more than a few things that still make using WP7 a little awkward.The LiveTiles, for example, are one of the cleanest, most polished looking experiences I have ever had on a smartphone. That is, right until you install a third party app. The experience allows you to set a specific color for the entire experience and change that at will. On top of the colors, your apps can display information on the tile like how many emails are unread. Developers have the ability to incorporate the LiveTile experience into their apps, but from what I could find many developers haven’t bothered. Even fairly major apps, like Twitter and Facebook, keep the color scheme to their own default colors and don’t change it in any way.Also, there’s this dedicated search button on the Lumia 900, next to the home and back buttons. When you press it, no matter where you press it, the button launches Bing Search. If you are in the email app, it doesn’t allow you to search through the mail for example. In fact, in most places, there’s a software search button that is to be used completely separate from the search button on the device. This is a new feature as a part of Windows Phone Mango, and a feature that I wish would get fixed because it’s a clunker.All told, however, if you’re not absolutely in love with a different mobile OS, Windows Phone is perfectly capable of delivering a quality experience.Easily the best phone for the priceThe most exciting part of the Nokia Lumia 900 is that it’s a great Windows Phone on AT&T’s crazy fast 4G LTE network. The L900 is the only Windows Phone to date with access to that network, and the only LTE non-Android phone on AT&T. The Lumia 900 is going to be joining the likes of the $299 Samsung Galaxy Note and the $49 Pantech Burst in the 4G LTE world, but it’s coming in at $99 on a two-year agreement. For the price, the Nokia Lumia 900 is absolutely the best phone on AT&T’s 4G LTE network, and a huge boost to the Windows Phone lineup.Nokia Lumia 900 – side standingNokia Lumia 900 – side standingNokia Lumia 900 – sideNokia Lumia 900 – iphoneNokia Lumia 900 – home stackNokia Lumia 900 – home sideNokia Lumia 900 – homeNokia Lumia 900 – frontNokia Lumia 900 – backThe Lumia 900 was loaned to us from AT&T/Nokia.