Smartphones have long seemed to be a good idea in theory. But in practice, they've often proved unsatisfactory.

By adding the programs and power of a handheld computer to the portability and voice features of a mobile phone, smartphones offer a much more useful combined device. But to date, most of those devices are a dissatisfying compromise, either giving short shrift to the phone or to the PDA features.

In recent months, both

palmOne

and

Research In Motion

have released new smartphones. Though both are improvements on past combination devices, palmOne's Treo 650 comes closer to the ideal.

The 650 is the latest iteration in the Treo line and the direct successor to palmOne's popular Treo 600. Available from

Sprint

for about $420 with a two-year service agreement, the new 650, like its predecessors, uses the Palm operating system, which means that users can easily run the thousands of programs written for Palm's handhelds. But with the Treo 650, palmOne addresses many of the shortcomings of its previous smartphones.

For instance, the company has added to the Treo 650 features that customers expect from a phone. The Treo 650 has dedicated "talk" and "end" buttons for phone calls, something the Treo 600 lacked. And the new device has a removable battery, one that users can replace temporarily if it runs low on a trip, or permanently if it loses its ability to hold a charge.

Coupled with the new battery is one of the features in palmOne's new

Tungsten 5 handheld: flash memory. This means that even if the battery runs out of juice or if users take it out of the device, the Treo 650 won't lose contact numbers or calendar entries.

The Treo 650 also includes some features that have become

de rigueur

on high-end mobile phones. PalmOne added a Bluetooth radio to the 650, which allows users to connect wirelessly to special headsets or to synchronize data with a computer sans wires.

Treo 650
palmOne's smartphone getting smarter

Like the Treo 600, the Treo 650 has a built-in digital camera. But the Treo 650's camera handles low light better and also offers the ability to record videos. And with an improved display, the new device can show off those pictures and videos much better than the older one.

But despite the improvements, the device is by no means perfect.

Although the company obviously tried to make the device more phonelike than it did in earlier models, the product still lacks in that regard. The Treo 650 weighs in at about 6.3 ounces, making it a bit hefty compared with most phones. And even though the device is much narrower than the first iterations of the Treo, it still feels wide and bulky, more like a walkie-talkie than a typical mobile phone.

Additionally, the device sometimes isn't as good as a typical phone. For instance, I had to use the touch screen too often for things like activating the speaker phone or to mute a call. The phone also doesn't include a built-in voice-dialing program. While such programs are available from third parties, you might expect one to come with the device, considering that they're included in phones that cost hundreds of dollars less than the Treo.

Likewise, some of the Treo 650's PDA functions are disappointing. In its CDMA (code division multiple access) versions -- i.e., those that will work on Sprint's and

Verizon's

(VZ) - Get Report

networks -- the Treo 650 won't be able to tap into the new 3-G networks. The result is that calling up Web pages can be painfully slow. Worse, the built-in browser often chokes on tables or layers, making many Web pages difficult to read.

Even though palmOne redesigned the Treo 650's keyboard, making its keys bigger, it still seems cramped, which can lead to the mistyping of letters or numbers. The device's camera offers less resolution than those available on far cheaper phones, and while the Treo 650's memory is more stable than that of the Treo 600, there's less of it available to use. This means that after a certain point, users will need to buy an SD storage card if they want to add more programs, store more videos or take more pictures.

The 7100t
Some raspberries for a new Blackberry

Even with these shortcomings, however, the Treo 650 is still more satisfying than the BlackBerry 7100t, RIM's new smartphone.

With the 7100t, RIM has attempted to repackage its popular pagers in a more phonelike form. The device, available in the U.S. from T-Mobile for about $200 with a one-year voice and data service plan, represents an attempt by the company to expand beyond its corporate user base into the consumer market.

The 7100t does have some great features. It weighs about 2 ounces less than the Treo 650. The lighter weight and its tapered design make it feel much more like a phone than does its rival from palmOne.

As a BlackBerry device, the 7100t also has the built-in ability to link up to BlackBerry servers to access corporate email in real time. RIM adds to the user's communication options by including instant messaging programs AIM, Yahoo! Messenger and ICQ.

Additionally, the device includes a speaker phone and Bluetooth.

The most unusual feature of the 7100t is its keyboard. RIM crammed a full "qwerty" keyboard into 20 keys by doubling or tripling up the letters and punctuation marks. The 7100t has a built-in program that translates users' key taps into sensible words. In typing email or instant messages, the feature works surprisingly well. Usually, it picked the right word while I was typing, without my having to select one of the alternate choices.

But for a higher-end device, the 7100t left me wanting more.

The device doesn't include a voice-dialing option, for instance, and it doesn't have a camera. Nor does it include an MP3 player or a picture or movie viewer.

Even if you could view movies or hear MP3s on the device, you wouldn't be able to store many of them on it. Though the 7100t includes a respectable 32MB of storage space, it doesn't have an expansion slot, so you have a limited number of programs or data you can house on it at any one time.

I also found the 7100t's user interface frustrating. I don't carry a BlackBerry, so I'm not all that familiar with the track wheel used to navigate RIM's pagers. Because the device doesn't have a touch screen or stylus or even a page-down key, you often have to endure seemingly endless scrolling with the track wheel to view Web pages or get through lists of information. A single click of the track wheel brings up a menu, meaning that to take an action, often two separate, successive clicks have to be made, something I found to be counterintuitive and slow.

And speaking of slow, Web browsing on the device is often excruciating. The 7100t's browser makes the Treo 650's look like a speed demon. But like that on the Treo 650, the end-product of all that waiting is often jumbled.