Microsoft's Windows 8 operating system launched back on October 26th to a lavish ceremony in Times Square and a marketing effort worth millions. After months of sales, Microsoft's Windows CFO, Tami Reller, sat down with The Verge to reflect on the launch and reveal what the company has learned in the 100 days Windows 8 has been available.

Thus far, Microsoft has revealed 60 million Windows 8 license sales for its new operating system, which is broadly in line with similar stats around the launch Windows 7. The figure doesn't tell the whole story though, as the Windows 8 upgrade cost is significantly lower and it's not clear how many are simply licenses sold to OEMs and businesses that aren't actively in use. However, Reller feels that Microsoft has had "a really solid start" to the launch of Windows 8.

Concerns over a PC sales decline have led some to question if Windows 8 will be able to boost the PC industry in the short- and long-term, or whether it's another Vista that the software giant might never recover from. Admitting that the holiday season wasn't perfect, Reller reveals that some hardware was "well represented" while some was not. "There was more demand for touch devices from consumers than we were able to meet with supply," says Reller, indicating that Microsoft and its OEMs need to do more to address the situation.

One particular area Microsoft has picked up on over the holidays is the importance of a retail presence. It's hard to imagine this wasn't clear before the launch, but Reller says there were a few winning devices over the holidays and "customers wanted to get their hands on" Surface over the holidays. With that in mind, Microsoft is expanding its own Surface RT distribution into Europe over the coming weeks, but there's no word on any plans for additional international retail stores.

Popular devices include Lenovo's IdeaPad Yoga 13, which Windows senior director Aidan Marcuss described as having "really good sell through" rates. "It's the sort of device that no one can keep in stock if they have it." Another popular choice among consumers is Acer's Aspire S7, Marcuss says "it keeps getting backordered." Both of these are touch-enabled devices running Windows 8, and Reller was keen to express it was a balance across Windows RT and Windows 8 on tablets.

Despite the promised balance, Samsung has pulled out of Windows RT in the US and HP says it has no plans to use the operating system on ARM-based chips just yet, describing the Surface as "slow and a little kludgey." I questioned Reller on Samsung's decision, but she refused to discuss it in detail. "With Samsung it's just a matter of where they chose to put their retail energy," says Reller. On the other hand, "just about every OEM has at least one Clover Trail design coming to market" this year says Reller — so it's clear OEMs see Intel's low-powered chips as a way to push tablets and hybrids to consumers.

Microsoft explained its decision to drop the Windows 8 Start button and Start Menu as one that relied on telemetry data that showed a trend away from Start Menu use. "Within the first 24 hours customers are definitely finding the desktop and doing what they need to do," says Reller. Microsoft claims over 90 percent of people find the most "important things" on the very first day of use. Marcuss appeared comfortable that users were learning the new user interface. Discussing the limited training for Windows 8, he says "what we think is that when you show them the one thing that matters, they discover it on their own and in context." It's a learning curve, but it seems to be working for some, despite strong evidence that users miss the Start Menu. The number of Tiles on the Start Screen doubles over the course of two weeks of use says Microsoft, propping up the 100 million app downloads figure, with the company recording 45 billion unique Live Tile updates by early January.

So Windows 8 is off to a steady start, not rushing out of the blocks, but what's in store for the future? Microsoft isn't ready to discuss Windows Blue just yet, a version of Windows that will likely debut this year — designed to optimiize the new UI and put Windows on a yearly path for upgrades. Questions over 7- and 8-inch Windows tablets are still largely unanswered too, while Apple is seeing high demand for its iPad Mini. Discussing the ability for Windows 8 to scale up from small tablets to large monitors, Reller believes this will allow Microsoft to adapt in future. "It's that flexibility and portability of Windows that gives us a lot of opportunity for the future wherever the market might take us." With Chromebooks on the rise and a continued consumer interest in tablets, Microsoft will have to ensure its Surface Pro tablet avoids any further controversy as the company looks to expand and generate greater sales this year.