Purely as a piece of hardware, this thing is nice! Really nice in fact. Without wanting to sound callous towards a certain Mr Jobs, this product is the perfect demonstration for stylus input, despite the former's distain for them.
It's a pity that Windows has to live on it, although I imagine it will be the perfect laptop replacement for those who depend on Windows software/support - particularly in huge install-bases like education. It's all very well criticising the OS, but many people are happy with it and will always find ways to 'combat' the latest the versions of Windows.
If Microsoft fell into one trap however, it's that they didn't properly consider the hardware requirements for Windows 8, and that in turn crippled both the original Surface RT and the OS. With Surface Pro 3, I'm more sceptical that the price points and specifications won't match the required levels of productivity. This is especially true now that cheaper external storage is available, and of course that we have now reached a point where Mac's themselves a gaining more attention even for just general computing, besides professional work. My worry for Microsoft is that, unless they form a campaign for how the Surface can be used in typical workplace situations, few will take it seriously.
But, much in the same way that Apple's approach with iOS and OS X is suited to other customers in other situations, the technology space is a much brighter affair when companies challenge each other indirectly and friendly, and whilst still focusing on markets that depend on their services. It's just a shame the way things have gone with Samsung.
Well done though, Microsoft!