Probably the best and most-reasoned analysis to date of why Windows 8 sucks.

Jakob Nielsen's Alertbox, November 19, 2012  

Windows 8 — Disappointing Usability for Both Novice and Power Users

Summary:
Hidden features, reduced discoverability, cognitive overhead from dual environments, and reduced power from a single-window UI and low information density. Too bad.

The full, excellent article: useit.com