Palm's upcoming Palm Centro smartphone is a big step forward in a small package, and now it's available in the UK. Updated February 8 2008

If, like us, you own an aging and increasingly bulky-looking Palm Treo but are reluctant to abandon the Palm OS, the Palm Centro may be the interim smartphone you've been waiting for.

We say "interim" because the Palm Centro we received this week still lacks features that are routinely available on competing Windows Mobile and BlackBerry devices - most notably Wi-Fi and GPS support. But to get a Palm-like package equipped with those amenities, we'll probably have to wait for the Linux-based successor to the Palm OS, which isn't expected to appear before 2008.

And given what the Palm Centro does deliver - Palm OS in its most contemporary and petite package yet - it's very attractively priced, at least in the US, where new users who sign up for a two-year Sprint contract and an all-you-can-eat data plan. The rebates associated with those contracts bring the device's nominal $400 price down to a palatable $100.

UK pricing and release details have not yet been released.

Slimmed-down hardware

The Palm Centro is significantly tinier (107x53x18mm) and lighter (119g) than its Treo kinfolk, and its smooth plastic case feels comfortable in the hand.

But the Palm Centro iis definitely made of cheaper stuff than the Treo. We found the removable battery cover a bit fragile and somewhat difficult to remove and replace. As we struggled to snap it into place, we worried that the cover might break. Similarly, the skinny black plastic stylus feels as though it might snap in two if you looked at it cross-eyed.

We confused by the small plastic door on the Palm Centro's side labeled 'Micro SD'. You can pull out the door with a fingernail, but the only way to insert the card is after you've first opened the battery cover. It would have made more sense if Palm had designed the door not to open at all unless the user removes the battery cover. As matters stand, the door is one more thing that might break if handled roughly.

Because the Palm Centro is so small, its keyboard keys are proportionately diminutive, and we feared that typing would be an unpleasant experience. But Palm has done a good job here. The keys are coated in a squishy plastic that keeps your fingertips from slipping, and the keyboard's smaller size didn't slow us down much.

The transflective 2.4in 320x320 colour touchscreen looks good, although it's smallish. The navigation controls - an oval pad; buttons for the phone interface, the main Palm OS menu, the calendar, and email; a red on/off button; and a green Send button - were responsive and easy to use.

A decent phone, too

To test the Palm Centro's performance as a mobile phone, we made several phone calls - with excellent results. The people at the other end sounded as good as on a landline, and they reported that we sounded great, too.

The Palm Centro supports Bluetooth, but we didn't have a chance to try it out with a Bluetooth headset (none was included in the package we received for testing).

Web browsing in the US with the Palm Centro's Blazer browser over Sprint's EvDO network was a sheer delight, especially since we're used to the rather pokey speeds of AT&T Wireless's EDGE network on the Treo. Pages seemed to leap on to the screen, especially from sites that have been optimised for mobile browsers. Even nonoptimised sites appeared quickly.

Email setup went smoothly, but to use the Palm Centro with my Windows Vista PC, we had to install Palm desktop software that doesn't support email synch over the USB sync cable.

One plus is that the Palm Centro supports concurrent instant messaging sessions with the three supported IM services (AOL, MSN and Yahoo--a welcome development for anyone who has friends on more than one of these services.