The "3" in Surface Pro 3 for me was the number of warranty replacements I had to go through before I finally gave up on the machine.
First failure was the battery ... apparently holding a charge for more than 30 minutes is desirable, but when the device is a sealed unit it's really hard to replace the battery.
Second failure was the screen stopped responding to touch except for about a 1" strip ... but that's glued to the unit as well and not replaceable
Third failure it just refused to power up at all and the tech couldn't work out what it was so got the final replacement.
The biggest problem for me though was the painful process of re-imaging the replacement machines (and this is a general Windows gripe) ... because of the convoluted registry it's not as simple as just doing a 'backup your apps and documents regularly and you can restore to a new machine" ... you have to reinstall programs (which is a pain if there are serial numbers or specific configurations that have to be re-created).
I've quickly learned that the only place to keep documents is in the cloud (because I've Office365 I use, and like OneDrive, but GDrive or Dropbox are equally useful) because when Windows borks it tends to bork hard.
I almost got a Dell XPS13 as the replacement, but I do a lot of video conferencing on the road and the camera position was just too weird, so now I'm using a Macbook Air (with Windows in a Fusion VM for the odd occasions I need it) and I'm very happy