The BlackBerry Storm 9500 is something of a departure for RIM, and not just because it's the first touchscreen BlackBerry. It's also a handset that has been jointly designed by its customers - the mobile phone operators Verizon and Vodafone.

Unlike some phones, which launch initially on one mobile phone network but are later rolled out and offered by several, the BlackBerry Storm 9500 is completely tied in to these two carriers. You can buy the Storm through Phones4U in the UK, but the only network you can buy it on will be Vodafone.

In some ways, this makes it easier for us to assess the BlackBerry Storm 9500's performance. Aside from the effectiveness of its touchscreen, it will live or die based on its 3G mobile connectivity. Vodafone's is very good, as we found when testing its over the air music downloads and when accessing the web.

The 158g BlackBerry Storm 9500 is physically larger and heavier than other BlackBerry phones. It has a brushed aluminium back with a rubber surround and a 75mm-deep transmissive screen that dominates its front. The usable area measures 80mm diagonally (61mm deep and 49mm wide). By comparison, the iPhone's touch-sensitive area is 81mm diagonally (64mm deep x 49mm wide) and it weighs 144g.

Unlike other phones, the BlackBerry Storm 9500's touchscreen is not just touchable but clickable, so to select an option or a specific area of a web page, you press down firmly. Once you get used to pressing a bit harder than you would on other touchscreen devices, it becomes quite satisfying, but we did have to train ourselves to apply that extra pressure.

The BlackBerry Storm 9500's onscreen icons are the large smart ones introduced on the BlackBerry Bold and are the ideal size for selecting with a thumb or finger. Typing on the BlackBerry Storm 9500 is wholly different experience than on previous BlackBerry smartphones, though.

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