The problem for Microsoft is that they are competing at the same time against laptops and tablets. For someone who's looking for a tablet, it loses badly to an iPad (the free space sticks out, but it is by now means the only place an iPad wins). For someone who's looking for a laptop, it loses to many laptops (in price, performance, ergonomics - whatever it is you care about, there's something that handily beats the Surface Pro).
Are there any people who are looking for something that's sort-of-a-tablet and sort-of-a-laptop, and are willing to get a device that is not competitive as either? We'll soon find out.
My own experience leads me to believe that until you have perfected a niche (neither laptops or tablets are there yet), extreme specialization always wins against generalization.