It follows the "safe-space" "you're not allowed to dissent" model pioneered by some "leftist" subs, and will ban people for having perfectly legitimate dissent.
It managed to exploit some loopholes in how reddit works to take-over the front page. The most interesting one was "stickying" new posts so they were shown on their front page. They did this to a new post pretty frequently. This let them
* Coordinate which posts got to the front page of reddit
and
* Exploited the reddit algorithm for determining "hotness"
For a while, 8 out of every 10 posts on the front page were from /r/the_donald.
It marks the first major incidence of the community engineering tools (that I believe were pioneered by subs like /r/shitRedditSays) being used by the right.