The Surface Pro represents a weird niche
The great thing about the PC platform is that you've got all kinds of choices.
You've got a traditional notebook with a 2-5 hour battery life, a large mechanical drive, probably an optical drive, a variety of screen sizes, and touch-screen or traditional input. In a price range between $250 and thousands of dollars.
You've got an Ultrabook with 5-8 hour battery life, an SSD, no optical drive, screen sizes between 11" and 14" typically, and touch-screen or traditional input - in a price range between ~$800-$1800
In the Ultrabook cataegory there are a lot of variables going on right now. Sacrafices and gains. It depends on where your value is on the features and benefits of the device. 64 or 128GB seems very small to me for the cost of the Surface Pro - but as an ULTRA ultrabook - it has a lot of things that really no other device approaches, for a price comparable to a top end iPad. The Surface Pro seems to be an emphasis on the Modern-UI experience and a tablet heavy use-model that *can* support real IA64/32 code. But both the Surfce RT and the Pro are focused on people who want something that is more of a competitor with the Android and iOS tablets, less so with traditional PCs.
I don't think that will be hugely successful starting out, honestly. I think that PC users who want a PC that has some tablet like features will be what drives adoption of Windows 8 and Windows 8 devices. Once Windows 8 gets some momentum, we might see the more tablet-driven devices like the Surfaces gain more traction. I see the Surface devices appealing to executives. The RT to general executives - and the Surface Pro to power-user executives who require a real Windows experience. Maybe. Also, to Microsoft loyalists. Which... fine. Apple has their loyalists, Android has theirs, and Microsoft also has theirs. The same basic kind of guy who buys a iPad Mini is the kind of guy who will buy a Surface RT or Pro.
