The Windows Mobile market is becoming increasingly crowded and, with the same engine under the hood, many handhelds are starting to look all too familiar. So some might consider Palm foolhardy to be abandoning its Palm OS roots (for now at least) and launching its new Treo as a purely Windows Mobile 5 device.

Pick it up, though, and you’ll discover that it isn’t just another identikit Microsoft PDA-style phone. Palm has focused on usability, including some improvements that sit on top of the WM5 platform. It’s retained some traditional Treo features, such as the switch on the top of the device to toggle between ring and vibrate, but also added innovations such as a threaded SMS chat client, Google search from the home screen, photo-based quick-dialling and transport controls when accessing voicemail.

The 750 is narrower than most PDA-style phones, so the keyboard is more closely spaced than usual, but we didn’t find it more difficult than its wider competition. We couldn’t help wishing that the device was a bit thinner, although the rounded back does leave it sitting nicely in the hand. And that’s great because many of Palm’s ergonomic tweaks have focused on making single-handed operation easy, including the dedicated Start and OK buttons next to the navigation pad.

We do have a few gripes, the biggest being the lack of Wi-Fi – a serious disadvantage compared to many of its competitors. We’re also concerned that the screen resolution is only 240 x 240 pixels: many corporate applications assume 240 x 320. We were also sad to see Palm’s proprietary connectors for synchronising and charging the device rather than standard mini-USB.

The Treo 750 is an exclusive joint venture between Palm, Telstra and Microsoft. The Telstra enhancements are arguably the most noticeable – including Foxtel streaming and Whereis mapping and tracking.

Until recently, Palm produced both the hardware and operating system for its devices, allowing it to create some highly-functional handhelds. With the move to Windows Mobile it’s lost that end-to-end control, but still used its experience to create one of the most usable WM5 devices we’ve seen. And it’s 3G (and HSDPA-compatible) too. Only the lack of Wi-Fi keeps it off the A-List.