With the launch of the Windows Phone 7 platform, Microsoft is entering a smartphone race that started in earnest more than three years ago.
So, what did it learn in those years on the sidelines?
Quite a bit, apparently.
The first three WP7 handsets - the HTC Surround and Samsung Focus from AT&T Wireless and the HTC HD7 from T-Mobile - will be available Monday for a $200 price tag.
I've spent a week with the Surround and overall I'm impressed.
It would be easy to call WP7 a half-baked smartphone platform, with its long list of omitted features.
But there are some real finds to make you want to take a peek.
This user interface is almost impossibly beautiful, even innovative.
Microsoft took a decided risk in shunning the grid-like, app-filled homescreen made popular by the Apple iPhone.
Instead, it completely rethought smartphone navigation. Information is stored in vertical queues that can be swiped to the left or right, topped with classy oversized labels.
Animated homescreen tiles can be set to launch frequent apps or tasks, such as calling a certain contact in your address book.
An apparent omission emerged as a welcome change: The phone's reception and battery life are not always displayed at the top of the screen.
That declutters the screen nicely, and a tiny finger swipe brings up the battery and signal-strength indicators if desired.
When you take a photo with the 5-megapixel camera, the image immediately becomes available just left of the viewfinder. To review the shot, swipe to the right and take a look - no more hopping between a camera mode and your roll of images. Smart.
The camera is also instant-on, meaning that you can hit the dedicated shutter button without unlocking the phone's screen first.
The Surround is clearly aimed to appeal to frequent music listeners and video watchers.
The handset features slide-out speakers that give outstanding sound for a mobile device. At the same time, a kickstand becomes available to prop up the device for comfortable video watching.
The Surround is screamingly fast - a credit both to its 1GHz processor and the Microsoft software.
Microsoft draws on some of its big brands to lend credence to the new smartphone line.
Each phone comes with a mobile version of Microsoft Office - the ubiquitous Word, Excel and PowerPoint - that gets the job done.
There is also integration with XBox Live, which no doubt will cause gamers to flock to the phone. You can play against other XBox Live users, getting the same personalized avatar you use on the XBox.
There are some critical omissions.
WP7 lacks the ability to copy and paste text - a seemingly easy feature famously lacking on the Apple iPhone at its 2007 release.
And since WP7 phones have no support for Flash video, it will be hard for users to find videos they can view.
Some Android users got the ability to play Flash videos this summer through the 2.2 software update. The iPhone cannot play Flash video, but plays the increasingly common HTML5 - another unplayable format on WP7.
There is also no support for multitasking - now standard for the iPhone and Android smartphones - so apps can't stay active in the background.
You also cannot turn the WP7 phones into a WiFi hotspot, a popular feature on competing phones.
During a jaunt through Monroe and Lenawee counties, the Surround on AT&T's network struggled in its turn-by-turn navigation compared to the Motorola Droid X from Verizon Wireless.
The Surround lost track of the GPS and lagged behind my actual position.
The AT&T turn-by-turn navigation is a $9.99-a-month add-on, compared to free navigation with some other phones and carriers.
While the call quality was superb on my end, my call audio dropped on the other end for a few seconds while I was speaking - an issue I face with other handsets on the AT&T network.
IS IT ENOUGH?
Microsoft has built a beautiful, adequately featured smartphone platform with its WP7 handsets. In fact, it's an absolute joy to use.
But it's entering a crowded marketplace dominated by Apple and a surging Google, which both have amassed millions of users.
The key for Microsoft - not known for moving deftly - will be how quickly it can work out the kinks.
Video calling, visual voicemail and tethering need to come soon.
Microsoft's consumer technology stumbles are numerous and well-documented, But there's no discounting that magic that comes with an entirely fresh smartphone experience - something we haven't seen since the iPhone's release more than three years ago.
We have that again in Windows Phone 7.
Explore further: Review: HTC One's interface sullies a great-looking phone