What do you want from a PDA, and what do you want from a phone? From the former, maybe a big screen, plenty of software, good on-board applications for managing your diary and contacts and maybe also for producing documents and spreadsheets. From the latter, good voice communications and probably data communications.

Suppose you want to combine both sets of features in a single small device? Then traditionally you are looking at either a smart-phone or a connected PDA. Now there is a third option; Vodafone's Power Handheld.

It might look like a standard connected PDA, but the Power Handheld has some significant differences. It runs Windows CE .NET (related to but not entirely interoperable with Windows Mobile 2003 for Pocket PC).

It comes with a range of on-board software including word processing and spreadsheet tools, e-mail and SMS management, Internet Explorer and Windows Media Player. It shares desktop data via ActiveSync (just like Windows Mobile 2003 for Pocket PC), and comes with a cradle.

It has a slot for your SIM and supports GPRS, and has built-in readers for popular document formats so it can cope with attachments. It will download e-mails at regular intervals via GPRS, or you can get them on demand.

It runs Macromedia Flash and pJAVA, and while applications written for Windows Mobile 2003 for Pocket PC need to be tweaked to run on the device, it will run those written for Microsoft's older Handheld PC platform.

Most notably of all, the Power Handheld has a slide out keyboard, which is larger than most found on portable devices and which is designed for bashing out the odd document as well as e-mail and SMS messages. To be honest it's not touch-typing standard, but it isn't bad.

Oh, and to accommodate both the width of the keyboard and desktop information viewing on the 640 x 480 pixel screen, the whole shebang operates in landscape mode, eschewing the usual PDA preference for portrait mode.

All this adds up to a hybrid device that Vodafone hopes will appeal to those who want plenty of data access and don't want to carry separate phone, PDA and maybe also laptop to get it.

The device works pretty well, but with some caveats. You will still need a laptop if you want to engage in real document production. You may want a separate mobile phone with which to travel light as the Power Handheld weighs 300g and measures 140 x 87 x 19.5mm - more than any PDA we've come across in recent times.

You should check out what third party software is around and be aware that the range will be more limited than usual because of the chosen operating system. And you may well find the battery lets you down. It's hard to test this kind of thing, but looping MP3s, which is a standard test for PDAs, delivered three hours and 14 minutes of life.

Despite the caveats mentioned above, this is an interesting machine, representing a step up from the usual smart-phone or connected PDA. If you need to type more than a few e-mails while on the move, the keyboard and landscape screen might make it worthwhile.