Surface Pro 2 already replaced my laptop/tablet, so it's no surprise that SP3 took it's spot.
It's a lot better in many ways, and I love that it's more powerful than SPro2 while being lighter than a 1st Gen iPad. The N-Trig turned out to be a lot better than I expected, and while I loved talking crap on iPad users that got their videos cropped/letterboxed, 3:2 did turn out to be more ideal.
The only thing I genuinely don't get along with is connected standby. On my SP2, getting 8-9 hours was normal... and I could give it a fair bit of stress (even through gaming) without the fans kicking into gear. I have NEVER gotten the SP3 to last as long as my SP2 did, it's fans will go crazy over light tasks, Connected Standby hides all power options but "Balanced," and it will ***** at me about my brightness setting affecting my battery if I ever go above 30% brightness. Yeah, I can easily kill it in regedit, but if I kill Connected Standby, it takes the sleep option with it and makes it such that I must completely shut down or my WiFi breaks (and somehow, waking from Hibernate takes longer than coldboot).
I never had this problem with SP2 or even the 1st gen SPro. I didn't mind the way Sleep worked on my SP2, and it seems that the battery drain is roughly 1% every 4 minutes with Connected Standby on. I'm about to just kill it for good and accept the fact that I'll have to power down then turn on per every session. It still coldboots in a couple seconds so that life can't be all bad.