So, I've been using the Surface Pro 3 with a mech kb since August and I have given up.
It is great if
- you never need to plug anything in ever
with only one usb port, you either need a freakish USB squid hub dangling out the side of your computer, or you never need to plug in a usb drive or anything and also use the keyboard.
This is the main reason I am abandoning the surface, it can't really be worked on without investing time in finding weird peripherals or hackarounds. Since your keyboard doesn't have a pointing device and stabbing the screen with a finger or the pen is actually quite difficult to do effectively when it's not in your other hand is basically not reasonable, you're going to want a bluetooth mouse also.
- you don't move a round a whole lot
the surface + dangly keyboard is unwieldy compared to a clamshell. Set up and tear down time is way slower than "get your computer out" since you have to get the keyboard, surface, and connecting cable (and hub if you have need of one) and plug all that **** in.
- you don't use it on your lap
I don't really care what MS marketing says. the kickstand is awkward and terrible on your lap or legs. Laying on the couch with the thing is no fun.