Related: "Review: Microsoft Surface Windows 8 Pro"

One quarter after the launch of Windows 8, questions persist about whether customers are embracing the new operating system. The latest bad news comes from Net Applications, which measures the online usage of different products, including desktop OSs. And this data shows that Windows 8 adoption is slower than that of the reviled Windows Vista.

Net Applications’ numbers are frequently misidentified as “market share”—indeed, even Net Applications makes this mistake—when in fact what the firm is really reporting is usage share, that is, a rough measurement of the OS’s real world usage compared to other OSs.

In its latest report covering the month of February 2013, Windows 8 commanded just 2.67 percent of overall desktop OS usage, compared to 44.6 percent for Windows 7, 39 percent for Windows XP, and 5.2 percent for Vista. (The most popular Mac OS X version, 10.8, lagged behind Windows 8 with just 2.6 percent usage share, so Windows 8 is at least outperforming the competition.)

The trend for Windows 8 is up, according to Net Applications, but slow. Most troubling, however, is that its usage share after one quarter trails that of Windows Vista at a similar time after its 2007 launch. Six years ago, Windows Vista controlled 4 percent of usage after one quarter in the market. I assume its common knowledge that, to date, Vista is widely considered the most disappointing Windows release of the past decade.

Is Windows 8 a Windows Vista-level debacle?

To date, Microsoft has maintained that Windows 8 is selling at roughly the same pace as Windows 7, which delivered a consistent 20 million license sales per month for its entire three year reign. A month ago, the firm announced that it had sold 60 million Windows 8 licenses, bolstering that claim.

There are of course questions about Microsoft’s numbers, which as always represent sales to PC makers and into the channel and not sales to end users. That’s why statistics like those from Net Applications are so important: They measure actual usage. And while Net Applications’ figures aren’t "perfect"—usage share is notoriously difficult to measure and results can vary widely—they’re still relevant and useful for measuring the impact of Windows 8 on the market. Certainly, the comparison of the Net Applications usage data for Windows 8 and Vista is telling.

I will say this: Windows 8 is aimed at a far broader category of devices than was Windows 7. So in addition to the traditional PCs—laptops and Ultrabooks, desktop PCs and so on—that Windows 7 targeted, Windows 8 is also aimed at a diverse new crowd of hybrid PCs that include slates and other tablet devices. That is, Windows 8 shouldn’t be compared solely to its predecessor. It should be compared to other device types, including Android tablets and full-sized iPads.

Net Applications doesn’t provide this kind of device breakdown. In fact, it comingles tablet sales with smart phone sales, making comparisons even more difficult.

But because Microsoft does occasionally provide license sales figures for Windows 8, we can at least compare these sales to that of its predecessor. And 20 million licenses a month is pretty much the minimum to expect from Windows 8: It should absolutely be able to maintain the pace of its predecessor, which was limited to just PC sales. But the potential market for Windows 8—PCs plus devices—is much bigger. Its inability, so far at least, to generate appreciable sales in the market for non-traditional PCs—i.e. devices—is troubling.

I’m not ready to call Windows 8 a full-blown debacle yet. 20 million licenses per month is still hundreds of millions of units a year, and PC sales will remain far above the quickly growing market for tablets for years to come. But anyone who was hoping for a quick reversal of trends should be disappointed by Windows 8’s market acceptance so far. For now, I must agree with the conclusions of market researcher NPD, which told late last year Microsoft that the release of Windows 8 neither helped nor hurt its prospects for the future.

One has to think that Microsoft was shooing for something a little more positive than that. And the constant speculation, and ongoing reaffirmations about a slow start, certainly aren’t helping either.