The HTC Touch Diamond P3700's elegantly diamond-contoured, sleek casing, TouchFLO 3D interface and 2.8in touchscreen create instant appeal.

Recently, PC Advisor reported the imminent sale of HTC's one-millionth Touch Diamond iPhone-killer – and just two months after its launch, making the Diamond HTC's fastest selling smartphone ever. Apple sold the same number of iPhone 3Gs in three days, but we're still impressed.

Indeed, some market researchers, including Canalys and Gartner, look on the strong demand for the HTC Touch Diamond as the result of Apple not only creating a higher mark to step up to with the iPhone 3G, but forcing the expansion of the overall smartphone market.

But forget the iPhone for a moment, and it's easy to see the instant appeal of the HTC Touch Diamond P3700's elegantly diamond-contoured, sleek casing, TouchFLO 3D interface and 2.8in (640x480) touchscreen, which auto-adjusts for different lighting conditions. Yet this beautiful craftmanship is spoilt as soon as the handset is put into use – a smattering of fingerprints littering the view.

And, as we pointed out in our first look review of the HTC Touch Diamond, for a handset built for touch navigation, this is an issue.

Nevertheless, we were impressed with the HTC Touch Diamond P3700's TouchFLO 3D, which allows you to look through your contact list by picture with the sweep of a finger if you add pictures to people in your contact list, or take their picture with the phone's 3.2Mp autofocus camera. For music listeners, the album covers show up so you can flip through them in the same way you look through the contact list. Of course, you can type in names as well by hand or stylus.

However, we found it difficult to get used to the necessary finger-sweeping movements and, until we had, the HTC Touch Diamond P3700's software seemed infuriatingly slow in use. Neither did we appreciate the way that pages often seemed to be scrunched up, with overlapping options or keypads obscuring text fields.

The HTC Touch Diamond P3700's 3.2Mp camera is a better example than that found on many mobile phones, but the lack of a flash is a low point for a high-spec handset. A second camera is provided for video calls. While 4GB of internal storage is provided with the HTC Touch Diamond P3700, the omission of a memory card slot for storing media is another mark against the handset.

The HTC Touch Diamond P3700 runs Windows Mobile 6.1, which will feel familiar to most users, and comes loaded with applications, including Microsoft Mobile Office and two browsers, Internet Explorer and Opera. Both worked well, although Opera has been better customised for one-handed navigation. You can zoom in by tapping the screen twice, or pan a website with one touch. The view automatically rotates if you turn the HTC Touch Diamond P3700 sideways to take advantage of the wider viewing angle.

The HTC Touch Diamond includes the usual Bubble Breaker and Solitaire games, but we much preferred the very simple game of Teeter, which uses motion sensors as you twist the handset to guide a ball through a series of holes. While no more exciting than firing the stylus at a group of coloured balls, or never winning a game of cards, we loved the fact HTC had made the effort.

NEXT PAGE: CoPilot in use on the HTC Touch Diamond P3700, and our expert verdict