The newest member of the Palm Treo smart phone family, the Treo 700wx, isn't just a cousin of the other models -- it's practically an identical twin of the existing 700w. Whether that's a good thing depends on your point of view.

No smart phones have begotten more buzz than Palm's Treo line. They are stylish, they are usable, they are full-featured, and the 700wx, which will be sold by Sprint Nextel, has the family resemblance with its features and finish. Its specs are identical to the 700w that's been sold by Verizon Wireless since January -- same 312-MHz Intel XScale processor, same Windows Mobile 5.0 operating system, same CDMA/EV-DO network technology, same 240x240 TFT touch screen, same 60MB of memory available to users.

The Treo 750wxIf you're among the noisy crowd of Treophiles that's been hoping for more -- more memory, perhaps, which was a particular sore point with the 700w, or built-in Wi-Fi, or the amputation of the stumpy antenna -- you're probably disappointed by the 700wx. You may not be thrilled by the price, either. The 700wx is expensive -- US$499 with a service plan, vs. US$399 from Verizon. Cingular will sell you a Treo 650, admittedly a lot less phone, for a lot less money: US$199.

(Each of the major cell phone carriers offers one or two Treo models, and the variations seem to have as much to do with the carriers' marketing and network technologies as they do with price or performance. For help with the you-can't-tell-the-players-without-a-program tangle of release dates and features, see a "A Treo Timeline."

But in the smart phone game, money is hardly a factor, since often it isn't yours. The choice of a smart phone is more likely to be made by a business's IT department than its users, and if you work in the IT department of a company with a contractual tie to Sprint, you may be thrilled by the 700wx.

The reason is the operating system. Windows Mobile 5.0 is built from the ground up to connect to an Exchange server, and it has strong support for corporate virtual private networks. You can synchronize your calendar and contacts information with Outlook on your desktop PC and even schedule meetings and invite attendees.

On the other hand, if you're like me -- a longtime Palm user -- you may not find much to like in Windows Mobile, and you might be happier with the Treo 700p that runs Palm OS 5.4.

Windows Mobile never lets you forget that it does an amazing job of squeezing the user interface of a very large operating system onto a very small screen. (The Windows Mobile Treos have lower-resolution screens than the Palm models -- 240x240 compared with 320x320.) There's a lot of UI to it, lots of buttons to click and menus to navigate, and yet some things I want to do I can't find commands for -- like, how do I "select all" in an e-mail folder?

The Palm OS, in contrast, grew up from a very simple, superbly integrated personal information manager product with a brilliantly intuitive UI. The small screen is its native habitat. But one result of this minimalist heritage is that it isn't as good at the connectivity tasks that drive business smart phone use -- secure wide-area networking for collaboration applications.

That said, there's so much to the Treo 700wx that just listing the features could take all day. It is truly wonderful what this device can do, even if it doesn't do all those things equally wonderfully:

- There is a 1.3-megapixel camera that also captures video, for example, and the Treo does a photo album and slide shows with pictures you take with it or load onto it. The pictures aren't wonderful, but they're certainly good enough for e-mailing.

- There's audio and video playback courtesy of the Windows Media Player bundled with the operating system. It's just fine, especially if you invest in an adapter for the 2.5mm headset jack and attach a pair of real headphones, or use a Bluetooth stereo headset. (The media-file library on the Treo can sync with Windows Media on your PC, something like iTunes and an iPod, but that's the hard way. Just stick some MP3 files on an SD card and plug it into the Treo's SD socket.) The sound quality through the unit's small speaker is awful, but it's not as bad as you'd expect.

- The Treo provides viewers for Office documents and PDF files that come as e-mail attachments or are loaded onto the device. Functionality is wonderful: You can edit Word documents and zoom into PDF files, but how much of that do you really want to do on a screen the size of four stamps?

This list could go on, but these aren't the important points about the 700wx. Did I say it's a cell phone? And a good one. It's actually stylishly petite, which isn't something you can say of the older BlackBerries, and it works well one-handed -- you can find or key in a number without having to devote both hands and the stylus to the task. Its speakerphone function works OK in a quiet setting. Some small UI changes have apparently been made, because "Hold" and "Mute" screen buttons now appear when your call connects. Early users of the 700w complained that those were buried in menus.

Even better than its cell phone functionality, the Treo 700wx is an e-mail tiger. It's easy to set it up for a variety of e-mail services -- Exchange mail, naturally, is almost automatic. MSN or Hotmail accounts are supported in the Treo UI, rather than logging into them in a Web browser. POP and SMTP accounts -- up to five of them -- are almost as easy. All I needed to know to set up a Gmail account was the username and password. For an ISP account, I had to provide the server names, but even that seemed easier than on similar devices.

Receiving e-mail, thanks to the EV-DO data link, is a breeze. Good-bye Wi-Fi hot spots; hello e-mail anywhere. But creating e-mail isn't quite as breezy. The keys on the Treo thumbboard are spaced more closely than on the standard BlackBerries -- a small difference, but I was acutely aware of it. (On the other hand, I'm glad to have a full alphanumeric key layout after reading reviews of the new BlackBerry Pearl, with its SureType keypad.)

One of the 700wx's neatest tricks is that you can use it as a modem to connect your laptop to the Internet from anywhere. Sprint's EV-DO network doesn't deliver the performance of desktop broadband service, but it's adequate for e-mail and browsing the Web. The ability to make a USB connection from the Treo to the laptop rather than using Bluetooth helps performance some.

Web browsing on the Treo, of course, is no better than it is on any other handheld device, but it's no worse, either. Applications designed for the small screen are OK -- and again, one advantage of the Windows Mobile OS is that it has all of .Net behind it, and companies that want to build or migrate apps to mobile devices will like that. (If you're more of a one-man army than a corporate soldier, you'll find that the larger number of applications available for Palm OS may make that device more attractive.)

With all of these features, the Treo 700wx is not something you just pick up and start using. You'll be digging into the manual before you make your first phone call, and setting up all the features takes a significant investment of time. But given the significant use you're likely to make of it, it's an investment that's well worth it.

David DeJean has been using and writing about mobile phones since they came with handles.