To understand the new Palm Centro smartphone, you have to understand who it's for.

There's nothing here for existing Palm Treo owners, and there's little to entice other smartphone users to switch.

Rather, the Centro exists to put more power into the hands of folks who are considering devices such as the T-Mobile Sidekick ID or LG's enV — inexpensive sub-smartphones with e-mail, text messaging and media options.

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It's no accident that the Centro looks a little like the BlackBerry Pearl. It's another instance of a smartphone manufacturer attempting to woo the younger crowd.

The Centro is bigger and heavier than the Pearl, but at 4.2 by 2.1 by 0.7 inches and 4.2 ounces, it's smaller in every dimension than the Treo 755p.

Palm saves space by shrinking the 320-by-320-pixel screen down to 2.2 inches (diagonal) and giving the device the world's most compact QWERTY keyboard.

Yes, the keys on this thing are really small. They're clear, grippy, rubbery nubs, which helps somewhat. But there's no avoiding the cramped feeling of this keyboard, especially when you're trying to dial a phone number.

If you want a better QWERTY keyboard, you'll need a bigger, wider device — it's that simple.

The Centro performs well as a cell phone. In our tests, reception was pretty good though not excellent.

The earpiece and speakerphone volume are both acceptable, but transmissions through the mouthpiece sounded compressed, and background noise made it difficult for callers to hear us clearly.

Transmissions through the speakerphone were surprisingly clear. You can also use a 2.5mm wired headset or a Bluetooth headset.

On our tests, the Centro's battery life was okay but not great, delivering a talk time of just over 4 hours.

One minor gripe: I wish there was a quick way to make calls from the home screen, as on BlackBerrys, where all you have to do is press the "phone" key to get to the dialing screen, where you can then use the touch screen or QWERTY keys to dial.

The Centro has no built-in voice dialing and no way to trigger voice dialing from a Bluetooth headset. But the handset does come with a demo copy of Nuance's interesting $6 MobileVoiceControl (MVC) application.

MVC lets you dial, check weather and stock quotes, and even add calendar entries and write short e-mail messages by voice.

Sadly, the software uploads your voice to a server somewhere in the clouds and then downloads the results, so it's slower than handset-based voice solutions.

The Centro runs the four-year-old Palm OS 5, with a 312-MHz processor and plenty of memory . There's 65MB free on board, and the device offers support for MicroSD cards up to 4GB. My Kingston 4GB card worked fine.

Like most Palm OS devices, the Centro feels really fast. Applications respond quickly to taps, and the screen redraws instantly, especially when compared with much slower Windows Mobile gadgets.

Also, like other Palm handsets, the Centro comes with easy-to-use contact and calendar applications and the option to sync via USB or Bluetooth with the free Palm Desktop or Microsoft Outlook, on PCs or Macs.

Sprint has done a good job of flooding the Centro with messaging options, too. There's a built-in instant-messaging client for AIM, MSN and Yahoo!, which runs in the background (though it shows only your "AIM Mobile" buddies).

Palm's basic VersaMail mail application handles POP/IMAP, but Sprint also includes its Seven-powered mobile e-mail app, which logs into AOL, Yahoo!, Windows Live, Gmail or POP/IMAP accounts. It's slick, smooth, efficient, and fun to use, though it doesn't display the formatting from HTML e-mail messages.

Also, for $10 a month, the client is supposed to hook into Microsoft Exchange accounts using the Outlook Web Access back door, which seems as if it's a great feature but wouldn't work for me.

The Centro's browser is the extremely tired, old, and basic-looking Palm Blazer, which displays Web pages but slaughters their formatting.

Also included is the most recent version of DocumentsToGo, the finest Microsoft Office document reading program anywhere. It isn't perfect, though. The app handled complex Word, PowerPoint, and PDF documents well but couldn't display Excel charts or graphics.

Even so, it functions as a full word processor, which is a great tool to have on a phone.

The Centro comes with a fine music player in PocketTunes Deluxe, which supports MP3, AAC and even purchased, protected or subscription WMA songs.

The device supports wired stereo headphones using its built-in 2.5mm jack, but only one of the four wired headsets I tested with the device worked properly — tunes would play through only one ear on the other three.

Also, the Centro doesn't support wireless Bluetooth stereo music headsets, limiting your music playback options.

The built-in 1-megapixel camera is nothing to get too charged up about. It's fine, with a tendency to blow out bright areas, but the pictures are sharp enough. The video camera mode takes large videos at 352 by 288, but I found them to be very jerky at 10 frames per second.

For playing video, Palm's Media app does a good job of transcoding video from your desktop to play on the device.

The Centro also comes with Sprint TV, Sprint's streaming media system with dozens of channels showing everything from music videos to full episodes of "Lost" and "Numbers."

The content is great, but delivery on the Centro is a big problem. I found CBS and ABC TV shows to be unwatchable, riddled by blockiness and scrambled images.

In theory, the Centro will work as a PC laptop modem on Sprint's EV-DO Rev 0 network. That should get you download speeds of about 400-700 kilobits per second.

But Sprint has already moved to the faster Rev A system, and I couldn't get the dialup function to work with my device.

In general, I'm concerned that the Centro's ease of use is compromised by its bugginess. I ran into several problems with my evaluation unit: In addition to the headphone support issue, I had to install On Demand and mobile e-mail twice each to get them to work.

Plus, the HotSync button on my USB cable didn't work, and Palm's Quick Install application showed an inaccurate amount of free space on my 4GB memory card. And there were some additional issues.

Palm's Treo 650, 680 and 700p all needed software updates after launch to fix bugs, and I'm sure the Centro will be the same.

The Centro may be built around 2005 technology, but at $99, that's enough for folks who just want to check e-mail and surf light Web sites.

Ultimately, the decision to make the Centro your first smartphone will come down to whether or not you can live with the bugs and the tiny keyboard, or if you want to pay more for a wider device like the Motorola Q, or something more feature-filled like a BlackBerry Pearl.

Editor's rating: Three and a half out of five stars.

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