By what metrics is it a failure? Because when I last looked at Microsoft's financial statements, their revenue was up due to the Surface (Profit was down for unrelated reasons).

I'm assuming you haven't used a Surface Pro but you can mark my words now, Apple will release a direct copy of the Surface within 3 years. The iPad Pro is a glorified iPad and will be utterly unusable for doing anything professional, so it's not a copy at this stage.