The HP Elite x3 is probably the best phone that nobody bought last year. The six-inch phablet has impressive hardware that matches those of the top Android and Apple handsets. However, the Elite x3 runs on Windows 10 Mobile, a platform with a minuscule number of users and with far fewer apps than its rivals.

It is a pity because the Elite x3 is the best advertisement for Microsoft's Windows Continuum feature, which lets you turn your phone into a PC by hooking it to a display, keyboard and mouse.

To facilitate this transformation, HP has bundled the Desk Dock with the Elite x3.

This accessory looks like a charging dock, but has two USB 3.0 ports, a USB Type-C port, DisplayPort and Ethernet port.

Place the Elite x3 on the Desk Dock and the phone automatically goes into Windows Continuum mode. In this mode, the Elite x3 shows, on the attached display, a desktop environment that is almost identical to Windows 10. There is minimal lag and it almost feels like I was working on my PC.

There are some limitations, though. For instance, app notifications still show up on the Elite x3 rather than on the monitor. Also, when I tried to add my Gmail account to the phone's Outlook Mail client in Continuum, the app says this was not possible. Instead, I had to enter my account details using the handset, and not the keyboard and mouse.

The e-mails in Outlook Mail also look pixelated and low-resolution on a 24-inch display.

For road warriors, HP sells a 12.5-inch laptop shell that has no processor, dubbed Lap Dock ($839). Connect the Elite x3 to the Lap Dock wirelessly (tap the phone to the NFC symbol on the palm rest), or with a USB cable.

However, I would not recommend the wireless option for the Lap Dock, as it felt choppy and laggy when I tested it.

Because the Elite x3 uses an ARM-based Qualcomm Snapdragon 820 processor, it cannot run legacy or desktop Windows apps written for the x86 platform.

This is a problem because HP has positioned the Elite x3 as an all-in- one device for business users. HP's solution is an app virtualisation service called HP Workspace.

This service, which works only if the Elite x3 is connected to the Desk Dock or the Lap Dock, lets you run legacy apps such as Microsoft Office 2013 that are hosted remotely on HP's servers. A one-year subscription starts from $828.

Firms can get HP to put their desired apps on the virtualisation service for their employees.

However, I found it frustrating to use because it felt like I was controlling a desktop PC remotely. Despite a good Internet connection, it felt choppy and laggy. Perhaps HP did not provide adequate bandwidth or server resources for the demo account that I tested.

As a smartphone, the Elite x3 comes with features you'd find on top models. Like the iPhone, it is rated IP67 for water and dust resistance, though it is not as good as the IP68-rated Samsung S7 series.

It has an iris scanner and a fingerprint sensor. I preferred the latter as it was faster and more accurate.

The Elite x3 has outstanding battery life, thanks to its 4,150mAh battery. After a day of moderate usage, I woke up the following morning to find the device with 45 per cent charge left. It will comfortably last 1.5 days without charging.

Windows 10 Mobile is decent enough if you use only mainstream apps, though the platform does not have any Google apps. Facebook, Instagram and Twitter are supported, as well as games such as Candy Crush Saga and Temple Run. Spotify and KKBox are available for music streaming while Netflix works for streaming videos. There is Uber, but no Grab.

HP deserves full marks for its efforts to make the Elite x3 The One Device for all your computing needs. I can even see HP convincing IT departments to try the Elite x3 as an alternative to laptops, especially for mobile professionals. But I doubt many consumers will ask for the Elite x3 in the shops.

• Verdict: Despite HP's best efforts, the Elite x3's impressive hardware is held back by the limited apps available on Windows 10 Mobile.