The meat of the linked article are pages 2 and 3, where the author gives a breakdown and commentary of the Mac and Windows approach to UI. Those pages are short with lots of graphics. Page 1 is stupid and page 4 is redundant. (This paragraph is for people complaining about the supposed length of the article and for people commenting on the title only)
The point of the article is that Apple has never made any dramatic changes to their core UI while Microsoft never seemed to settle on one that worked. While I disagree in many respects, the author makes a reasonable case.
The truth is that for most windows (and even mac users), they tend to be locked in to their OS of choice for other reasons and just deal with whatever UI they get. The lesson is more relevant in the general sense and applies to all manner of other GUI software. Windows users might be stuck with Windows but what stopped Ubuntu users from jumping ship when Unity made arbitrary unwanted changes to the interface? What stops Firefox users from switching to chrome or Opera when upgrades break functionality?
I think the bigger problem with Windows 8 was a broader problem that I saw articulated in a thread on reddit.
The thread was about how it seems like next-gen game companies seem to treat releases like they are beta releases. Many of the games for the PS4 and Xbox One are riddle with bugs. Companies seem to have gotten to comfortable with the fact that they can easily release updates post-release, and it's gotten to the point where they are releasing unfinished software to customers who expect it to be a finished.
Major problems with Windows 8 that should never have made it past QA/UAT:
1. Missing start menu button. Extremely confusing jump from 7. Fixed in 8.1
2. Confusing full screen start menu. Remedied in 8.1 with tutorials and better UI cues (down arrow for unpinned applications, embedded search bar on all applications page)
3. On Desktop, files should not open in metro apps by default. (still not fixed)
There should have been a longer beta testing period, and Windows 8.1 should have been Windows 8.
So really, I think the more important point is the mentality of the release cycle. Windows 8 was teased long before it was finally released, so there was a "why is this thing they promised us taking so long just release it already" effect. Apple, on the other hand, tends to hold off on announcing their products until shortly before they're released. There's a "it's been a while since Apple released something new, I wonder when they will release the next thing" effect, which allows them to wait until products are more releasable before actually announcing them
I wouldn't say missing start menu button was "fixed" in 8.1. All they did was put a button there that had the same functionality as that corner without a button already had.
The point of the article is that Apple has never made any dramatic changes to their core UI while Microsoft never seemed to settle on one that worked. While I disagree in many respects, the author makes a reasonable case.
The truth is that for most windows (and even mac users), they tend to be locked in to their OS of choice for other reasons and just deal with whatever UI they get. The lesson is more relevant in the general sense and applies to all manner of other GUI software. Windows users might be stuck with Windows but what stopped Ubuntu users from jumping ship when Unity made arbitrary unwanted changes to the interface? What stops Firefox users from switching to chrome or Opera when upgrades break functionality?