The Surface Pro 3 has a 12 inch screen, matching the Samsung Galaxy Pro tablets. It is also thinner, lighter and more portable than a MacBook Air. It is being marketed as the tablet that can replace your laptop.
You can read more about it here: http://www.pcadvisor.co.uk/new-product/tablets/3520725/microsoft-unveils-surface-pro-3/#ixzz32L16UA4z
It all looks pretty good. It also comes with a surface pen which lets you write and draw. Really hoping these will be inexpensive to replace, you just know you will lose it!