The tagline for the HP Elite x3 is catchy: "One device that's every device." But can this upcoming 6-inch phablet be the only computing device you will ever need for work?

For starters, it can lighten your bag, because it can replace your smartphone, laptop or tablet. It can also simplify your work flow because all your work-related apps and documents will be on a single device. There is no need to move from one device to another.

But there is a catch: the Elite x3 runs Microsoft's Windows 10 Mobile, a platform that has largely failed to lure consumers from the Android or iOS camp.

As a result, HP is not selling the Elite x3 at telcos and retail stores. It is instead targeting enterprise users with the Elite x3's secret weapon: the Windows Continuum feature in Windows 10 Mobile.

This feature automatically adapts the Windows 10 user interface to the type of screen. For instance, when you connect the Elite x3 to a larger, external display, it will show a desktop interface similar to what you get on a Windows 10 laptop.

Universal Windows apps that support the Windows Continuum feature will show more content to make full use of the larger screen, compared with the mobile versions.

In other words, Windows Continuum is the key to turning the Elite x3 from being just another smartphone into an all-in-one mobile computing device.

However, the Elite x3 uses a Qualcomm Snapdragon 820 chip, not an Intel processor. Hence, desktop or legacy Windows apps have to be rewritten to support the Elite x3. This is a potential deal-breaker, especially for companies that depend on older, legacy apps.

To tackle this problem, HP has created an app virtualisation service called HP Workspace. This cloud-based service will let Elite x3 users run legacy or desktop apps remotely. Some of the apps already available in HP Workspace include Microsoft Office 365 and an invoicing software.

Complementing the Elite x3 are two HP accessories. The HP Desk Dock connects to an external monitor and comes with additional USB ports and an Ethernet port.

The Lap Dock is for road warriors who require a keyboard and mouse. It is basically a laptop shell without a processor. You connect the Elite x3 to the Lap Dock via a USB cable. You can also connect the Elite x3 wirelessly via the Miracast wireless display standard to use the Lap Dock's keyboard, mouse and display.

I like the thin bezel around the Lap Dock's 12.5-inch display. The keyboard has good key travel. There are additional USB Type-C ports at the sides, which can be used to charge the Elite x3.

However, the Lap Dock feels as heavy as some ultrabooks, thanks to a 47 watt-hour battery said to last more than 12 hours.

Of course, the Elite x3 is still a smartphone. It even has high-end features you'd expect from a flagship model, including a 2,560 x 1,440-pixel Amoled display, a fingerprint sensor and a 16-megapixel rear camera.

More importantly, the Elite x3 has a relatively large 4,150mAh battery that, according to HP, will provide around 12 hours of usage.

You can even charge the Elite x3 wirelessly.

During my brief hands-on with the device, the Elite x3 fits in my hand nicely despite the 6-inch screen. It feels balanced with some heft (it weighs 195g). The fingerprint sensor is at the back, which makes it easy to unlock the device with one hand.

I do not see the Elite x3 replacing my current smartphone and laptop. The Lap Dock is not that much lighter than my laptop.

But the Elite x3 may appeal to certain users, such as those in sales or industries like healthcare, retail and warehousing.

HP says that the pricing for the Elite x3 and its accessories, along with the subscription fees for the HP Workspace service, will be revealed closer to availability. The Elite x3 is expected to launch in September.