If you believe Microsoft's official line on the Windows 8-based Surface tablets, you're probably wondering why so many people already seem to consider the new slate a disappointment. After all, the Surface Pro sold out! That means people want it!

Reality may actually be a little more complicated than that. Since Microsoft declines to release official Surface sales numbers, a number of analysts have come up with their own data — and it isn't as flattering as Microsoft would like.

Numbers range from between one million Surface RT tablets sold during the fourth quarter of 2012 to just under 700,000. The Surface Pro launched on Feb.9, but no estimates are available just yet. For comparison, the new iPad sold 3 million units during its first weekend alone.

Yikes. Some analysts even think the reason the Surface Pro sold out is because Microsoft didn't ship enough units in the first place.

But Microsoft is having none of it. Speaking to the MIT Technology Review, the company's CEO Steve Ballmer defended the Surface, although he didn't quite say whether or not he's pleased with the sales.

"I'm super-glad we did Surface," said Ballmer. "I think it is important — and not just for Microsoft but for the entire Windows ecosystem — to see integrated hardware and software."

Trying to quell the suspicion that Microsoft's attempt to enter the hardware manufacturing business is half-hearted, Ballmer tried to assure everyone that Surface is — no, really, truly is — a "real business."

"Surface is a real business," he said. "In an environment in which there's 350 million PCs sold, I don't think Surface is going to dominate volume, but it's a real business."

So there you have it. The Surface line may not be off to the greatest start, but Microsoft is in it for the long haul. Ballmer considers it integral to the company's future to offer the same user interface across all devices: desktop PCs, laptops, mobile devices and tablets. 

Despite Microsoft's insistence that it's fully committed to the Surface, things might not have always been that way. The company tried to convince computer makers to produce quality touch-tablets to promote Windows 8, but many balked at developing high-end devices for an unproven operating system. When faced with resistance, Microsoft decided the best way forward was to move on its own. Only time will tell if that was a smart decision.