While it's a little thing (pardon the pun), the fact that the Surface Pro is scaled better and more usable with fingertips in desktop mode will help save calls to IT or to your family IT person (probably you, if you're reading this). True, the Acer W700 has better battery life, but the Surface Pro doesn't require as much tweaking to make it useful out of the box.
It also has better ergonomics than the Acer Iconia W700 and better behavior in desktop mode (where you run almost all your programs). The Surface Pro has business compatibility (i.e., it can join Windows domains and use corporate level software), a selection of keyboard covers, and is intelligently set up for touch and portable use. The digitizing stylus is an added boon for those who would like to take notes, draw art, or fill out forms right on their tablet screen.
Now the big question: Is it worth it? If you need a very portable tablet that has full Windows 8 compatibility, powerful components, and a 1080p touch screen, the Microsoft Surface Windows 8 Pro is your tablet.
