Nielsen accused Microsoft of ignoring the cumulative weight of experience of user interface design in its simplistic "Modern UI" design. "The new look sacrifices usability on the altar of looking different... There's a reason GUI designers used to make objects look more detailed and actionable than they do in the Metro design."
Providing the "settings menu" as an example, the Modern UI design made it difficult for users to know where to tap or to click to conduct a process. "Where can you click? Everything looks flat, and in fact 'Change PC settings' looks more like the label for the icon group than a clickable command. As a result, many users in our testing didn't click this command when they were trying to access one of the features it hides," wrote Nielsen.
And "live tiles", one of the innovations that Microsoft has trumpeted most loudly, also came in for stinging criticisms for distracting users with useless but intrusive graphics, while failing to provide genuinely useful information.
It works well when "used judiciously", wrote Nielsen. "Unfortunately, application designers immediately went overboard and went from live tiles to hyper-energised ones."
He added: "The theory, no doubt, is to attract users by constantly previewing new photos and other interesting content within the tiles. But the result makes the Surface start screen into an incessantly blinking, unruly environment that feels like dozens of carnival barkers yelling at you simultaneously."
Live tiles often lacked useful identifiable data, so users also found it difficult to identify the files or apps they wanted in Windows 8.
The criticism of Windows 8's user interface shortcomings is especially stinging in view of the departure of Steven Sinofsky, who led the development of Windows 7 after the calamitous disaster of Windows Vista and Windows 8 – to be replaced by Microsoft's user interface specialist Julie Larson-Green.
Given his all-round criticism of Windows 8, Nielsen was keen to assert that he did not "hate" Microsoft: "I happen to think that Windows 7 is a good product and that Windows 8 is a misguided one. I derived these conclusions from first principles of human-computer interaction theory and from watching users in our new research. One doesn't have to hate or love a company in order to analyse its UI designs."
He concluded: "I'll stay with Win7 the next few years and hope for better times with Windows 9. One great thing about Microsoft is that they do have a history of correcting their mistakes."