I don't use the Surface Pro 3, but my friend does. He used it as his work "laptop" for the duration of a gig at one company. The dock attachment is a good addition if you want it for that purpose, but its tablet form factor makes it work better than any laptop I've seen for being productive off the office desk, like sitting in front of the fireplace and writing a bunch of text. His use has convinced me that if I ever need to get a new personal laptop (my company provides me with the only one I use) I would get the Pro 3.
I use a desktop as my main dev machine, and I haven't tried to supplant it with any of these portable machines, just supplement. I do run Visual Studio, WebStorm, Photoshop, etc. on the Surface though, no problem, to code and push real features.
The docking station and a large display or two would probably be a must for using it as a primary machine. I haven't tried the docking station myself, but I've heard lots of good things about it.