With rumors about the release of Office for iPad has been swelling in recent weeks, the naysayers have crawled out of the woodpile out back and declared that the battle was already over. Microsoft was too slow to market, we were told, and iPad users had already moved on to other semi-compatible office productivity solutions, such as Apple's free iWork products. This isn't the first time the doubters have underestimated Microsoft's strongest business, and it won't be the last. But they have never been more wrong than they were about Office for iPad.

Related: It's Official: Microsoft Releases Office for iPad

At the time of this writing—a full week after Microsoft announced Office for iPad—Word, Excel and PowerPoint occupy the top three slots in the free iPad apps list respectively in Apple's App Store. I assume this is in the United States only, but based on reports, this situation is identical throughout the world. They've occupied these top three positions since they were released.

More impressively, perhaps, Word is the #7 top grossing app, while Excel sits at #14 and PowerPoint is at #39. This means that a surprising number of iPad users are actually signing up for Office 365 subscriptions at $99 per year and up and doing so through the app, because that's the only way for these apps to make money through Apple's store. The vast majority of Office for iPad users already have an Office 365 subscription, obviously, so these are new customers, and new customers who prefer to do things through their iPads.

Related: Details Emerge About Office for iPad

Folks, there is only one way to interpret this data. Office for iPad is a resounding, unqualified smash hit.

This shows us that the pent up demand for these apps was fairly enormous. And that Microsoft was right to launch this product, not just in general, but the way it did so, by positioning Office for iPad as a full-featured set of apps and not the watered down, minimal environment it ships on smart phones as Office Mobile. I had feared that Microsoft would succumb to a last minute gut-check and, worried about Windows cannibalization, it would dumb down Office for iPad. It did not do so.

You can read about my overall impressions of Office for iPad in my review, and I've been bolstering that with further articles about this suite on the SuperSite for Windows. What I've come to understand after using these apps for a bit over a week is that ... wait for it ... they're really good. I know, that reads like an astonishingly unsophisticated thing to say. But in my capacity as a reviewer, I have to look at various products through the lenses of the expected users, and of course in this measure, Office for iPad is right where it needs to be. But I also look at everything I review with an eye towards my own needs. And in this way, Office for iPad is surprisingly good.

Granted, I do write about Windows and Microsoft technologies for the most part. So it's not like I'll be switching my workflow over to the iPad, which among other things lacks support for side-by-side apps and other niceties we just expect on the Windows side. But I write books, and I've edited my most recent book, the 575-page Windows 8.1 Field Guide, in Word for iPad. And it doesn't just work. It works well. The performance is excellent, and the capabilities are exactly what I need, from an editing perspective. Were it not for my focus on Windows, and the iPad's lack of side-by-side app usage, I could use this app to get real work done.

What excites me further about Office for iPad is the same thing that excites me about Office 365 or virtually any other major concern at the software giant: These apps are on a rapid release cycle and will be updated regularly going forward—as often as every two weeks, I was told—as needed. My guess is that we'll see a bunch of updates up front since these apps are brand new and user feedback will quickly uncover the most important missing bits. (You can't print from these apps, yet, for example.)

For those who are worried that Office for iPad sounds the death knell for Surface specifically or even Windows generally, my advice is to relax. As I noted late last week in "Some Thoughts About Office "Touch" for Windows," Microsoft was very careful in describing Office for iPad as a product that was custom tailored to the device. And I think that theme will carry over to the "Metro"/"Modern"/"Immersive" (seriously, Microsoft, pick a name) Office apps that it will deliver to Windows 8 and RT user sometime this year. That is, I think those versions will be even more powerful, since Windows devices are so much more full-featured, from a productivity standpoint, than iPad. (And yes, you can expect an Android Office this year, too.)

Could Microsoft have released Office for iPad sooner? Yes: My sources tell me this suite was ready last year but that Microsoft reengineered it completely for iOS 7. Should they have released it sooner? I've often thought so and said as much. But given how successful this launch event went, it's pretty clear that they're actually not too late to the iPad party. In fact, it's fair to say from a productivity standpoint, that party is finally just getting started.