A smart phone with a slide-out keyboard isn't exactly a rarity these days, but this model stands out from its rivals because it doesn't have the girth of a Russian weightlifter. In fact, it's only marginally thicker than your average candybar handset. The other big news is that it runs the brand new version of Microsoft's mobile phone OS -- Windows Mobile 6.

Orange will be branding the handset as the E650, so if you're on that network you'll be able to get it free on contract. Others will be able to pick it up for around £270 as the HTC S710.

Design

The HTC S710 is the best-looking Windows smart phone we've seen in a long time. The mirrored metal surround that circles the front of the phone contrasts perfectly with the black styling of the rest of the handset and the rubberised plastic on the rear makes it comfortable to grip in your hand.

The slick design is all the more impressive because the body of the phone hides a full Qwerty keyboard. To get at the keyboard you just push the screen to the left. When the keyboard pops out, the bright and crisp display automatically switches from portrait to landscape view giving it much the same feel as a clamshell PDA.

The slide-out keyboard is a decent size and has backlit keys

We wouldn't exactly describe the keyboard as spacious, but it's just about large enough for two-finger typing. The keys are also backlit, so you'll have no problems tapping out text messages or emails on the way home after a night out.

Of course, you don't always have to use the slide-out keyboard to control the phone. Every element of the software can also be driven by the keypad on the front. This has twin soft keys at the top along with a large direction pad that makes it easy to move through the menus. The number keys, however, are a tad on the small side, so popping out the Qwerty keyboard is definitely the best option when you need to type long text messages or emails.

To sync the phone with your PC there's a mini-USB port on the bottom. This is also used for charging the handset and for hooking up the headphones for use with the built-in media player.

Features

This is the first handset we've seen that runs the latest version of Microsoft's phone OS -- Windows Mobile 6 -- which was formerly known as Crossbow. Apart from spruced-up icons, the bulk of the user interface doesn't look all that different from the previous version.

There have been some tweaks here and there, though. For example, the call history is now listed next to names in the Contacts list and the Calendar has been updated with a handy new appointment preview pane at the bottom of the screen.

Microsoft has also improved the messaging functionality. You can now resize text in emails, which is neat as it means less scrolling when reading long messages, and for the first time you get support for HTML emails.

The other major update is the inclusion of new XT9 predictive text messaging. It differs from the standard T9 software by the inclusion of automatic spell correction and next letter prediction. What this means in practice is that a list of predicted words appears at the bottom of the display as you type. So if you want to enter 'follows', you only have to type 'fol' and then pick the full predicted word from this list. It's useful for those who are slow at texting, but speed demons will often find it's faster to just type the whole word rather than move through the predicted list to find the right one.