I like them. I haven't been a fan of all the flat and monochrome icons that have been popular during the last decade.
All the icons start to look the same and converge on basic shapes with no color to distinguish features. Plus, many designers no longer put labels on buttons/icons, compounding the problem.
As the article briefly touches on, the monochrome icons made a ton of sense when color was added externally to the icon by the system. Windows Live Tiles would add brand colors as backdrops and other parts of Windows would color icons their brand color in foregrounding. Some problems with that approach was Live Tiles never got the general acceptance they deserved and the "smart" display surfaces like Live Tiles and Notifications that knew about branding colors and such were never the only places icons might appear (especially for cross-platform apps).
The icons are fine, but some are identifiable as Microsoft/Windows, and others are completely generic.
oh joy, more soulless google-like material application design. I hate to sound like some nostalgic old fogey, but I wish microsoft had kept windows 7 alive.