The Surface RT, imho, seems pointless. But I guess it could be decent in the enterprise, BYOD or "provided device" market... it would be wonderful there, in fact, but most companies aren't going to have a majority of their work done in Metro interface apps. It's very much possible, but the app ecosystem is far too young and most enterprises are very slow to adopt both new hardware and/or new software. And while using Office on them isn't bad, that can't be the only selling point for those devices.
If Microsoft can keep the Surface RT around for a few generations, it might become quite successful. Convincing themselves to gamble on that? I doubt they will.
The Surface Pro, on the other hand, is flipping awesome for what it is. I love it.
Granted, I don't use mine much, but I knew that going in.
I suspect it might get a decent amount of use in my near future, if things go well. Picking up a new camera and equipment, the Surface Pro will go in my bag with me and I'll have my editing software on there. If I build my portfolio fast enough and can get some freelance business going soon, it'll definitely be used to quickly show some stuff to clients or check whatever.
Admittedly, the Surface Pro would be that much better if it launched after the new Intel chips drop last this year.
Now, they just need (or need to force someone to get to it already) to get those teased battery-toting keyboard docks out already. If I can have one of those, I'm completely sold on this thing and then some. It's why I still keep an eye on any news from IBM for the Thinkpad Helix, but it's more expensive.
It's a terrific "can be a tablet when I want" device, but obviously can't hang with the form factor and battery life of a true ARM-based tablet. As it stands now, it can't be a great laptop but it can be a decent laptop. With a functional hinged keyboard dock, that would solve the only issue there.
If it's to be a third-party product (the battery keyboard - they never mentioned hinged but I can't believe it would be anything else), hopefully it's a well-designed one and matches the device. I'd love to see a first-party version, but who knows.
It's not for everyone, for sure. The Surface RT, at this point, I wouldn't even recommend. The Pro - you should know if it's up your alley or not. It won't sell at mobile OS tablet-levels, it's just not possible. I don't think any single laptop makes that kind of dent in the overall market, and that's very much what the Surface Pro needs to be measured as. The Surface Pro, to be successful, does not need to pull in "tablet" sales numbers.