What Microsoft didn't say about Windows 10 is important to know

There's a lot to like about Windows 10, the next version of Microsoft's flagship operating system. But the tech giant has also worryingly left unanswered a lot of important questions about the software.

At an event at its Redmond, Wash., headquarters last week, Microsoft gave developers and the press the latest peek at Windows 10. I've not yet tested the software, but from what I've read and seen from the webcast of the event, the new operating system appears to address many of the worst flaws in its predecessor, Windows 8. It also offers a bunch of cool and innovative features, such as a Siri-like personal assistant that will work on your desktop computer, the ability to stream Xbox games to your PC, and support for HoloLens, a new kind of computerized eyewear.

Best of all, Microsoft will be offering it as a free upgrade to many existing Windows users and will continue to upgrade the software to those users at no additional cost.

But I was troubled by some of the things that Microsoft didn't fully discuss. Most notably, the company envisions transforming Windows from a piece of software that receives major, but infrequent, updates into something that resembles a Web service like Gmail or Facebook that sees much more frequent incremental changes. But it's not clear at all how that will work in practice or how much control consumers will have over the updates.

For all of us who stuck with Windows XP or Windows 7 instead of upgrading to Windows Vista or Windows 8, that's an important detail to know.

Microsoft gave consumers their first glance of Windows 10 last spring and has gradually revealed more details during the last nine months. It's clear that the design of the software is in part a reaction to the widely negative response to Windows 8.

As the company has shown before, Windows 10 will bring back a version of the traditional Start menu. It will also be much more flexible than its predecessor, adapting to how users are interacting with it. Unlike Windows 8, the new software will recognize whether consumers are using a touch screen or a keyboard and will give them the choice of which mode to use.

Microsoft is also finally developing a version of its Office apps for touch-screen Windows tablets, which will allow users of such devices to avoid having to delve into the old desktop. And it showed off the ability to run traditional Windows apps either on the desktop or in the touch-screen interface.

Microsoft is also trying to make it much more seamless for consumers to switch among Windows devices. Many of the company's own apps will be universal ones, meaning that they will run on Windows phones, tablets, PCs and even Xbox game consoles. The Outlook calendar, for example, will look largely the same regardless of what device you are using. So too - finally! - will the settings menu, which will now be a single app in Windows, rather than existing as three different features. With the new software, outside developers will be able to build universal apps also.

In a move that's clearly aimed at getting more people to switch more quickly to the new software, Microsoft says it will offer the new software as a free upgrade to many Windows users and will continue to update it for free on an ongoing basis. That's a significant price break for consumers, who have often had to pay $100 or more to upgrade their copy of Windows to new versions.

And Windows 10 will have other goodies to offer. I'm particularly excited that Microsoft is bringing Cortana, its Siri-like personal assistant, to the desktop; it's something I've long wished Apple would do for the Mac. Likewise, I'm intrigued about the possibilities of HoloLens, which looks like a cross between Google Glass and Oculus Rift, even if I'm a bit skeptical about how many consumers will actually want to wear the device on a regular basis.

But as much as I like what Microsoft has done with Windows 10, I'm worried about some of the things it didn't say about it. For example, Microsoft said that certain existing "qualified" Windows users will be able to upgrade for free to the new software. But it didn't define who exactly would be qualified or eligible for the update. Some Windows users clearly will be left out; on a blog post, the company noted that "some editions" of Windows would be excluded from the upgrade offer and that it would set certain - but similarly undefined - hardware and software requirements for it.

What's more disconcerting is how the company will update Windows 10 after users install the software. Company officials painted a vision for the software where updates would happen in the background, automatically, and no one would worry any more about which version they were running, because everyone would be on the latest iteration.

That vision is undeniably attractive for Microsoft and software developers; it means they'd have to support far fewer versions of Windows. But it's unnerving for a lot of us end users, because Microsoft has a poor track record for upgrading its operating systems. Two of its last three major updates - Vista and Windows 8 - were largely rejected by consumers because of their flaws. While Windows XP eventually became a solid operating system, it didn't start that way; Microsoft had to issue three big updates to fix numerous bugs and close major security holes.

Because of such issues, experts often advise waiting to update software until the bugs are identified and addressed. But if Microsoft's vision for Windows 10 comes to pass, consumers might not have that choice. They might get the updates whether they want them or not.

So, as good as Windows 10 sounds, I'm wary of it nonetheless. Upgrading to Windows 10 may be great in the short term, but it may also mean getting involuntarily stuck with another Vista somewhere down the line.