The first thing you notice about the Compaq iPaq palmtop is just how thin it is. At 130 by 15.9 by 83.5mm, its the thinnest colour CE-based device to date. Weighing 170g it's also moderately lightweight, and the silver and grey finish make it stand out in a crowd of PDA's.

The iPaq is among the latest PDAs released with the third generation of Windows CE, referred to by Microsoft as the Pocket PC operating system. Powered by a 206 MHz Intel StrongARM processor, with 32MB of RAM and 16 MB of upgradeable ROM, the iPaq doesn't feel as sluggish as previous palm-size Windows CE devices have done, which is a good start.

A lot of thought has gone into the design of the iPaq's five function buttons that appear on the front panel. The power button is well recessed to avoid accidental activation of the unit and the four programmable application buttons are also recessed, but are nevertheless easy to push and activate.

Also on the front panel is an automatic light sensor that can regulate the intensity of the unit's sidelight, helping to prolong battery life, although this is a little disconcerting if the lighting changes rapidly while you're using the device.

The supplied USB cradle follows the sleek design of the unit itself, and looks a bit futuristic, while a serial cradle is available as an option (£19 + VAT). The iPaq fits firmly into the cradle - sometimes a little too firmly, in fact - with or without the provided jacket. You can also charge the embedded 950 mAh Lithium Polymer battery in the cradle or by simply plugging the AC adapter into the bottom of the unit, which could be useful if you are on the move. A light on the front panel blinks orange to indicate that the battery's charging, remains steadily orange to indicate that the battery is fully charged, and lights up green to remind the user of an appointment.

The TFT touch-screen display is reflective, with a 12-bit colour depth and 240 by 320 pixel resolution. Image quality is very good, especially if high levels of screen brightness are selected, although inevitably this will gobble up the available battery power quite quickly.

For expandability the iPaq uses Compaq's Expansion Pack system. These packs attach to the iPaq and give functionality with whatever technology is featured, a bit like the Handspring Visor. The first of these packs to be released is the Type II Compact Flash jacket, (£25 + VAT) which lets you use industry-standard CF cards with the iPaq. Also supplied with the review machine was the newer PC Card jacket (£61 + VAT). Although the Expansion packs provide an excellent platform, the lack of a Compact Flash slot as standard is a disappointment, as the jackets add bulk and weight, making the device decidedly less sleek than it is in its bare form.

The Pocket PC operating system provides numerous applications, such as Calendar, Contacts, Pocket Excel, Pocket Word, Tasks, Voice Recorder, Notes, Pocket Internet Explorer, Calculator, Solitaire, Inbox, File Explorer and Media Player. Added to these are the extras that Compaq adds to the iPaq, such as ROM, QMenu, Asset Viewer, Qstart, QUtility Picture Viewer and Backup, most of which are at least partly self-explanatory. There are plenty of extra applications on the Microsoft and Compaq CD-ROM supplied with the iPaq, so you're unlikely to want for toys to play with on your new machine.

Perhaps because it's taken time to get to market, the iPaq Pocket PC is potentially one of the most functional palm-format devices you can buy, and arguably the best implementation yet of Microsoft's third-generation palm-size Windows CE platform. We're not completely convinced by the add-on pack format, though.