Maybe this just isn't obvious enough, but The Surface Is Not A Laptop. It is a Tablet.
Buying a Surface Pro to be your main development machine is nearly as silly as buying an Android Phone or an iPad to be your main development machine.
Which to me means I have no reason to buy one. The only reason I was interested in the Surface Pro is because I thought it might be a full fletched laptop replacement that could also be a tablet when the need arose.
My laptop is my primary work machine. At work, I connect it to an external keyboard and monitor, and I don't have another computer there. I use it on the go as well, but I rarely actually code on it that way because even a 13" screen is too small for that. I also use it at conferences for e-mail etc., and on flights to watch movies.
Those last two occasions are the only situations in which I think it'd be nicer if I had a tablet. However, they don't pop up often enough for me to want to own a separate tablet. I already have a laptop, smartphone and Kindle, so why would I want yet another device to carry around with such a limited range of usage scenarios? I'd never use a tablet at home, because I have my desktop PC and since I live in Tokyo I'm never more than 4 metres away from it while inside my house. I'd never use it at work, because that's what my laptop is for and it's not a productivity device. I wouldn't use it while commuting because I read during that time and e-Ink is vastly superior to any LCD screen for that.
So I don't own a tablet, because if I did buy one it'd be nothing more than a toy that would rarely see any real use.
The Surface Pro piqued my interest because it sounded like it could take over the job my laptop did (dock at work as my primary machine, occasional on the go work) and also be a tablet for simple e-mail or video stuff when I needed that.
But it sounds like the Surface Pro will be too limited in capabilities to stand in for my laptop, which is a shame. Hopefully its successor will be better, or a third party OEM will make something better suiting my needs.
It's s shame, because this is a unique opportunity. It's something no other tablet can do. To me this is much more interesting than having a separate tablet, and furthermore it's something only Windows 8 can do. No other PC OS can also be used on tablets. No other tablet OS can also be used for real work. MS should really try to capitalize on that more.