First I'll do my own mini-Review. I only used the Surface Pro in Best Buy, so this is not from an extensive time with it. (I had a Surface RT, for nearly two weeks, before deciding it was flat out bad and taking it back.) I agree with Mary Jo Foley (link inside the links below): it is worse that the Surface RT.
It is heavy. It is warm, to the point it would make your hands sweat if you were using it as a tablet. Seriously, if you were playing a game and got the CPU usage up, it would be warm enough, you'd fear dropping it from your sweaty hands. Microsoft did a better job with the cooling fans than I expected, but they are still there. You still need to be at a desk if you want to use the keyboard. It is much snappier than the Surface RT. It is totally not worth the price.
As a tablet, it fails spectacularly, it is THICK, it is shaped wrong, it has poor battery life (some reviewers saying as little as 3 hours), oh and worst of all, it runs Windows 8.
As a laptop, it fails spectacularly, you can only use it at a desk or other flat surface, its screen is too small to reasonably use all that resolution, the keyboard and trackpad (even on the Type cover) are substandard.
Who would buy this? What would they do with it? I cannot conceive of a scenario where you would not be better off taking the same money, buy a small ASUS laptop ($509) and then using the left over money to buy a nice Android tablet($349) and a Samsung ARM-based Chromebook($249) Total: $1,107. A 128Gb Surface Pro (and you will need the extra space the 64GB model has less than 32GB free) with "Type" keyboard is $1,129.
Anyway, here is links to summaries of reviews:
Microsoft's Surface Pro: The reviews are in - Apple 2.0 -Fortune Tech
Microsoft Surface Pro gets tough early reviews | Reuters
Microsoft Surface Pro review roundup: Is a Windows 8 tablet worth $1000? - Liliputing
Review roundup: Microsoft's Surface Pro is about compromises