HTC has officially announced the HTC One M9, its new 2015 flagship smartphone.

The HTC One M9 is a refinement of the HTC One line, aiming to improve on the HTC One M8, rather than completely reinventing the phone from the ground up.

The design closely resembles that of the 2014 device, but the quality has been increased for a tighter, more precise and luxurious finish. HTC said it looked for inspiration in the luxury watch market and that's evident. 

The front is now a single piece containing the display and BoomSound speakers - freshly enhanced with Dolby - that fits into the rear metal body. There are four colours at launch including gold and gunmetal grey, but the real skill is in dual tone finishes.

Through an extensive manufacturing process, HTC has finished the silver-gold and M9 with a dual tone anodising, giving a silver back with gold around the sides. There's also a pink and gold model, offering the same meticulous attention to detail.

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The display stays as a 5-inch, 1920 x 1080 panel (440ppi), with the handset shrinking a little over the previous model, which should save too much drain on the 2840mAh battery.

Internally there's a octo-core Qualcomm Snapdragon 810 chipset with 3GB of RAM to give it plenty of oomph, along with 32GB of storage, expandable via microSD card.

The phone launches on Android 5.0 Lollipop and debuts Sense 7, which brings a whole world of customisation options through Themes. You can create a theme from a photo, with options to customise just about every element, from the shape of the icons, to the touch controls running across the bottom of the display.

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Dolby is now on board providing a surround sound effect through the front-facing BoomSound speakers, with Dolby tuned headphones in the box too. 

But the biggest change is in the camera department. There's now a 20-megapixel camera on the rear and the 4-megapixel UltraPixel sensor has moved to the front. That should make for great selfies, and plenty of detail on the rear camera, which now offers 4K video capture.

The HTC One M9 is expected to hit shelves at the end of March, the price hasn't been confirmed, but we'd predict that to be around £579.