The HTC HD2 is a high-end smartphone with a large touch screen and a customisable user interface, which comes about as close as you can currently get to the experience of Apple's iPhone on a Windows Mobile handset.

Available now on O2, Vodafone and T-Mobile, the HD2 is the first Windows phone to feature a capacitive touch screen, according to HTC. It is also one of the first handsets we have seen running Windows Mobile 6.5 Professional, and boasts built-in applications for social networks such as Facebook and Twitter, along with one or two other interesting features.

With its larger than average 4.3in screen, HTC's Sense user interface, and a powerful enough processor to drive it all, the HD2 makes touch input much more practical and usable than on many other handsets we have seen.

On the downside, this screen makes the phone itself a little large to easily fit in a pocket, and it is also costly to buy as a SIM-free device, with resellers such as Expansys offering it at a whopping £499. This aside, we found the HD2 to be one of the most impressive smartphones we have used.

Specifications
In hardware terms, the HD2 is similar to many other high-end smartphones, with HSPA support up to 7.2Mbit/s, 802.11 b/g Wi-Fi, Bluetooth, and built-in GPS capability.

Our evaluation handset came from HTC itself, but we were able to test it using a 3G SIM kindly provided by Vodafone, which we found provided a decent download speed for browsing the web.

The handset is based on Qualcomm's 1GHz Snapdragon processor with 448MB RAM and 512MB Flash ROM, and storage can be expanded via a micro SD card slot.

At 120mm x 67mm, the HD2 is noticeably larger than most other rival devices such as the iPhone, but it's just 11mm thick. It also weighs more than the iPhone at 157g, but this makes it no heavier than RIM's BlackBerry Storm2.

This size is dictated by the handset's large 4.3in screen, and HTC has put the real estate to good use with its Sense user interface, making most of the on-screen controls a decent size, whereas it is all too easy to tap the wrong control with many other touch screen devices.

Just below the screen are a set of buttons, two for the phone call and hang up functions, plus a home key, back button, and Windows menu key. Aside from the volume up/down control on the side of the HD2, all other input is via the screen. A micro USB connector for recharge and PC connection is on the bottom of the case, along with an earphone jack socket.

With HTC's Sense, the home screen is dominated by a simulated Rolodex-style flip clock and a background animation showing the local weather. This screen can also be customised with quick link buttons to applications, individual contacts, or bookmarked web URLs.

At the bottom of the screen is a scrolling strip that links to commonly accessed functions such as people (contacts), calendar, mail, internet, music, and photos & videos. Sliding a finger along this allows you to easily bring up the one you want.

Several of these, such as messaging, calendar and mail, actually provide a more user-friendly front-end than the built-in Windows applications. HTC has also applied its Sense look and feel to many of the Windows settings screens, making them more usable than would otherwise be the case.

Tapping the Start menu at the top of the screen brings up the Windows Mobile menu, which in version 6.5 features larger icons arranged in a hexagonal grid to make them easier to tap with a fingertip.

Overall, we found the user interface on the HD2 very responsive, and we could zoom through lists with just the flick of a fingertip, plus the larger screen area seems to make it easier to touch the control you intended to. We still found that we often tapped the wrong on-screen control by accident, but this is a drawback common to every touch-screen phone we've ever used.

However, while some applications, such as the Opera browser, automatically change screen orientation if you twist the phone round, others do not, which is an annoying (if trivial) bugbear.