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, decentscreens 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 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 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.

In addition, Microsoft, unlike Apple, has ceded prominent home-screen real estate to the phone makers and carriers so they can push their own apps, like subscription-based TV and navigation services.

To be sure, Windows Phone 7 has a few advantages. These include built-in mobile versions of Microsoft Office (present for years on earlier Microsoft-powered phones) and of its popular Xbox Live gaming service, which also interacts with Xbox game consoles. There is a nice feature that allows the camera to be used quickly, even if the phone is locked. And search works particularly well, including a mode that allows you to enter search commands by voice from any screen. Phone calling also worked just fine, with few failed calls, good voice quality and easy connection to a Bluetooth device I tried.

But I couldn't find a killer innovation that would be likely to make iPhone or Android users envious, except possibly for dedicated Xbox users. Even the built-in Office can be replicated with third-party Office-compatible apps on competing platforms; and the iPhone and Android phones also can interoperate with Microsoft's corporate Exchange email, calendar and contactsystem.

So for now, I see Windows Phone 7 as mostly getting Microsoft into the game, and replacing the stale, complicated Windows Mobile system that preceded it. It will get better. The company is already working on a copy and paste system, and said it is coming early next year. But, today, I see Windows Phone 7 as inferior to iPhone and Android for most average users. It's simply not fully baked yet.

The main feature of Windows Phone 7 is the Start screen, which takes the form of a long vertical list of tiles that can represent either an app or a hub. The phones lack multiple home screens or traditional folders for grouping apps. These tiles are dynamic: They can show things like rotating photos of friends.

Microsoft doesn't intend for you to place every app or feature on the Start screen. Instead, some apps, like games, go automatically into one of the special tile hubs, which combinerelated functions. And all other apps pre-installed or added to your phone go into another long master list you can see by flicking aside the tile view or tapping an arrow.

It's a clean, simple, different approach. But there is a downside. As you 'pin' your favorite apps, contacts, photos or Web sites to the Start screen, the list of tiles grows longer, and you have to scroll further and further to reach some. There is no shortcut for getting back to the top of such a list, as there is on the iPhone.

The hubs have a level of social and functional integration seen on some Android phones and on Palm's webOS operating system, now owned by Hewlett-Packard. For instance, in the People hub, you not only see your local contacts, but those synced from Facebook or Microsoft's Windows Live service. This hub, like the others, borrows the elegant interface from Microsoft's failed Zune music player, so you can flick left and right to see just recent contacts or to see your friends' status updates. But the People hub doesn't have Twitter.

Microsoft sees this combination of tiles and hubs as a 'glance and go' interface for quickly seeing important information without opening apps, as on the iPhone. But I was disappointed that more information wasn't presented on the tiles. For instance, unlike in some Android apps and widgets I've used, a stock market tile and a weather tile I downloaded didn't show on their surfaces the latest information.

The calendar, which syncs with Exchange, Windows Live, or Google, can't sync with Yahoo or MobileMe, and lacks a week view. The email program syncs with a variety of services, but lacks a unified inbox.

Another downside for some users: The phones can be used in horizontal view for photos and Web pages, or for typing email, but some screens, like the Start screen and hubs, are fixed in vertical mode.