That release date felt acceptable at the time, particularly considering it was more of an experimental device as opposed to part of the core Surface lineup. After all, the Surface Pro 7 and Surface Laptop 3 were revealed at the same event and were always going to attract most of the attention. 

However, as the Duo continues to be teased by Microsoft, it has become clear that it's being marketed as more of a mainstream productivity device. 

Senior Director Frank Shaw took a picture of it lying on the desk in the same way you might do with a smartphone, while Chief Product Officer Panos Panay has highlighted its camera capabilities. This has led to speculation that the Duo could even arrive early, although nothing has been confirmed yet. 

On its official website, Microsoft describes the Surface Duo as as a device which will "reimagine productivity on the go". It's hard to understand what that might look like. While the above cameras are considered one of the pillars of a great smartphone, it's unlikely to be a reason for buying the Surface Duo.

Laptops, and more recently tablets, are highly effective for remaining productive while out and about. The allure of a physical keyboard still remains strong, and it's unclear what's Surface Duo's virtual version will be like.

The emphasis on the device being pocketable discourages use of external accessories, but this form factor places serious limitations on productivity. Each 5.6in screen offers barely a third of the screen real estate on a regular laptop, especially if you need regular access to the keyboard. 

Even when using for pleasure, it's hard to see how the Surface Duo won't get quickly frustrating. There's no reason to consume content on a dual-screen device, while there will be a whole new learning curve for something as simple as texting. The second screen may be able to act as a controller for mobile gaming, but few apps will be optimised for this kind of gameplay yet. 

Microsoft hasn't manufactured smartphones since the Lumia line was discontinued in 2017, so the Surface Duo looks to the closest thing to it. It will make headlines as the first Microsoft hardware to run Android natively, but in truth it barely resembles the majority of handsets on the market.

That's perhaps the point. The tried-and-tested smartphone design has led to a stagnation of the market, and Microsoft is one of the few companies that can allow a product to flop and not see a significant hit to profits. 

Nonetheless, it's difficult to see what purpose the Surface Duo can fulfil in the long term. It may turn out to be an exciting embellishment to enthusiasts' tech lineup as opposed to a direct replacement for any current devices. 

If Microsoft is set on this form factor, the Surface Neo looks like a much better bet.