If there's one word we'd use to describe the HTC HD7's OS, Windows Phone 7, it would be 'unified', with the OS visually bringing all its functionality into a Zune inspired system of panels and panning, on the great big HTC HD7 screen, it looks very immersive, clean and controlled. The start menu (home screen) aggregates these panels into tiles aligned in a very simple vertical grid of two columns and multiple rows. Each tile takes up a fair chunk of the screen, with only 8 tiles fitting on the screen at any one time. On first glance, it seems simplistic for a home screen, blurring the lines between home-screen and menu, however, it is also cleverer than it looks, displaying key live information within tiles, encouraging the user "glance and go", as Microsoft put it, and dip in when appropriate.

Slide the homescreen out of the way (a swipe from right to left will do the job), and Microsoft bestows a simple list of applications on your screen. All these can be pinned to the start menu with a long press, or just opened from the list. It’s worth noting, if you’re left handed that it’s not as usable as if you’re right handed as your thumb will cover the tiles and swiping right to left to get the menu up is un-intuitive.

Now we've covered the two start-up pages (the start menu and application list), we can move on to one standout feature of Windows Phone 7, the visual flourishes. Select anything (and we mean anything), and rather than a simple menu transition, there will be a cascade of current tiles revolving out of the frame, and a stream of new elements either panning, revolving, or emerging into the frame. These would look like overkill on any other OS, however, thanks to the styling of Windows Phone 7 being so very simple, it works to have this one extravagance.

At the heart of this simple styling are the themes. Go into settings, press the themes option and you can "Change your phone's background and accent colour to suit your mood today, this week or all month" as Microsoft puts it. As far as background colour goes, your options are whittled down to black or white, which is a good, minimalistic way to ensure the user doesn't make Microsoft's shiny new phone OS ugly. Accent colours are applied to app tiles and standout text. To compensate for the minimal choice of background, these can be one of 11 colours, green, red, blue, orange, pink, brown, lime, teal, purple and magenta. This simplicity lends itself to an identity Microsoft are clearly trying to attribute to Windows Phone 7, with a sophisticated font, Segoe WP, large, clear tiles and smooth Zune type experience.

The interface is intuitive with very few layers of menu and is very clearly marked out. We found ourselves looking for an Android menu button at times with many applications lacking the extensive functionality their Android counterparts may have (i.e. selecting which Google Calendar to display if you have multiple under one account), however, Microsoft have clearly placed limits on the things doable on a Windows Phone 7 handset in order to keep the experience simple and clean, and they succeed for the most part. It won't be for everyone, but thanks to the ease of use, visual flare and the fact that there really is no lag, there is definitely a place in the market for this OS with nothing else like it available.

Phonebook, Messaging and Organizer:

As a phone, the HTC HD7 works well, with a good dialler sporting big responsive keys. Type a number in and there is a save button underneath the dialler. It's all very easy and intuitive. The phone book falls under the people tile. This offers very tight integration with Facebook, with a right swipe from your contact list taking you to friend's recent updates. The search capacitive button adapts its function depending on which menu you're in, so contacts can either be scrolled through or searched for directly as expected. Long press the Windows capacitive button to activate the voice dialler. We found this worked exceptionally well out of the box.

Messaging is also a pleasure for the most part. The keyboard is a fantastic size on the HTC HD7 both in portrait and landscape thanks to the 4.3 inch screen and the predictive text is very good indeed. We could type full messages with very good speeds with few if any mistakes. There are no long pressing on the keyboard (except to caps lock) and there are two layouts of letters (upper and lower case), and two layouts of symbols. The keyboard looks so clean and simple with no gradients in sight that the minimalist in us can't help but enjoy it. Without copy and paste, functionality is hampered slightly, though Microsoft promises this in the near future.

Organizer features pre-installed include alarms, calculator, calendar and HTC's unit converter. The calendar is the most finger friendly we've used in a while, looking very clean and feeling really intuitive. Adding appointments is simple, and the whole experience was a pleasure in every aspect other than the aforementioned section regarding multiple Google calendars (you can't choose which calendar under your Google account to use). All other organizer features work predictably well.

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