In short, Stalkers got raised so that the difference between their damage and hit points and those of Scrappers was about half of it was before. They lost the "Critical on Held or Slept" enemies, and got a random crit like Scrappers, but it increases the more allies are on your team. (With more allies as a distraction, you get more chances for an "attack of opportunity") Plus, if you Assassin Strike a target and don't kill it, everyone else around him loses some ability to hit, and may be Feared.
The above is totally unneeded since the links cover it, but I figured what the hey. 
Thanks for the summary, Jade. That's some good information.
Currently on Virtue:
Jinrazuo - Crab Spider
RWZ All-Pylon Solo Run
I'm interested in creating a Stalker for GR when it comes out. The last time I played a Stalker was when CoV first came out, and frankly, the experience wasn't too great. I felt like they were scrappers with blaster survivability. Maybe I was doing the whole stalker thing wrong but I'd like to give it another shot.
From reading some threads on here I keep hearing about a 'Stalker buff' that occurred at some point. Would someone be able to elaborate a bit on this?
Currently on Virtue:
Jinrazuo - Crab Spider
RWZ All-Pylon Solo Run