I have a Surface Pro. Got it the first day released, but wanted to spend some time with it before commenting. Basically, the intent behind it is a miracle, and the product is a solid delivery. The machine is great, fast, everything I wanted, and unfortunately a bit heavy. The Windows 8 experience is actually kind of cool. The metro view is responsive and easy to configure, and the switch to and from desktop is easy. The biggest issue I'd see for most people is the battery power. With power saving measures, I can get 6 hours out of it. If I wanted to play games, I would be very frustrated with the 3-4 hours from the couple of free games I tried (more correctly, I let a kid try- I don't really play games.)
The pen is fantastic, I use it for way more than drawing. That is probably the most surprising bonus, and I really hope I don't lose the pen, the connector is lame when the machine is in my bag, never holds it. Storage was never an issue for me as I regularly move data to and from devices and my 2TB drive so I was prepared for the transient nature of my data now. The display is good, but expect the next version will be even better. Still, I work on high res images and it is capable, and for my truly color accurate needs, it drives my HP monitor quite nicely.
The sum total is that I really love it. I was clinging to a 6 yr old vaio umpc, and an 8 yr old G5 in my home office waiting for something that was a full computer in a flexible tablet form. It is almost that, and for the few disappointments (weight and battery,) there is an equal or better benefit that I hadn't considered a must have, but now can't live without (the pen and the type keyboard.)
I am definitely an early adopter of stuff, so I have a bit more bandwidth for beta. This is way better than beta, but I think a few modifications could make the next version a huge hit.