The question is whether the new version, which can be run on tablets and smartphones, along with the traditional PC, can satisfy the needs of both types of users.
"I am very worried that Microsoft may be about to shoot itself in the foot spectacularly," said. Michael Mace, the CEO of Silicon Valley software startup Cera Technology and a former Apple employee. Windows 8 is so different, he said, that many Windows users who aren't technophiles will feel lost, he said.
Microsoft is releasing Windows 8 on Oct. 26, and it doesn't plan to cushion the impact. Computer companies will make Windows 8 standard on practically all PCs that are sold to consumers.
Speaking to Wall Street analysts on Thursday, Microsoft's chief financial officer Peter Klein said he isn't very concerned that user confusion could slow the adoption of Windows 8. When Microsoft introduces new features, he said, people eventually realize that "those innovations have delivered way more value, way more productivity and way better usability." That's going to be true of Windows 8 too, he said.
Instead of the familiar Start menu and icons, Windows 8 displays applications as a colorful array of tiles, which can feature updated information from the applications. For instance, the "Photos" tile shows an image from the user's collection, and the "People" tile shows images from the user's social-media contacts. (Microsoft is licensed to use AP content in the Windows 8 news applications.)
The tiles are big and easy to hit with a finger — convenient for a touch screen. Applications fill the whole screen by default — convenient for a tablet screen, which is usually smaller than a PC's. The little buttons that surround Windows 7 applications, for functions like controlling the speaker volume, are hidden, giving a clean, uncluttered view. When you need those little buttons, you can bring them out, but users have to figure out on their own how to do it.