The problem with Windows 8 on traditional PC form factors is it deliberately ignores ("blows up") the model that's been fixed over 20 years in users' heads and replaces it with a new model they've attempted to design from scratch from first principles. It's not that the new model is especially complex or badly designed on its own terms, it just clashes with the model people already have in their heads.
That is also why people often say the Windows 8 UI works well with touch, but is unusable with mouse and keyboard. The inherent usability characteristics are actually not hugely different between input methods, it's just that with touch there's not as much competition in people's heads from an entrenched existing model.
That is also why people often say the Windows 8 UI works well with touch, but is unusable with mouse and keyboard. The inherent usability characteristics are actually not hugely different between input methods, it's just that with touch there's not as much competition in people's heads from an entrenched existing model.