Well, "leaker" is a misnomer. She's a traitor, a spy, an oathbreaker, and ultimately
a very stupid young woman.
At the most basic level, she stole classified documents and gave them to an unauthorized person. She did it for one of the four primary motivations of espionage (sometimes referred to as MICE) in that she was ideologically motivated. Like Jonathan Pollard, she will have supporters who will say she was a patriot, just trying to help save her country. And like Pollard's supporters, hers will be wrong. She is a traitor who put her own motives ahead of the interests of her nation, her oaths, her integrity, and her future. Make no mistake, Reality Winner (yes, that's actually her name) has destroyed her future in order to score some political points. She sold out sources and methods the NSA uses to defend ALL of us in order to make "#NotHerPresident" look bad. And the worst thing is, what she stole didn't even prove what she probably thought it proved.
The document in question reveals that Russians hacked into voter registration data at a third party contractor. Not to change it, nor to change vote totals, but effectively to steal identities. In other words, nothing that could influence the 2016 election. And this stupid, stupid person decided that the law, her oaths, national security, her integrity, and her very future were unimportant enough that she should steal that information and release it to someone who would make sure the Russians (remember them?) would know we know they did it. An action which helps them to figure out how WE knew, which shuts down an avenue of intelligence gathering, or even potentially gets an actual live person KILLED (never forget the true cost of espionage; it's not "documents" or "words", it's actual lives).
I do feel some small pity for her. She ruined her own life with her stupidity. And worse, she did it to reveal a document that still does not show what she thought it did (the Russians hacked the election and made it so Trump won). But mostly I feel anger. She knew better. She had mandated yearly training that told her that she would be caught, that told her the consequences of being caught, that told her how stupid her idea was. But she ignored all that, betrayed her employer, her co-workers, her friends, and her nation... all in an effort to score political points (which she failed to even do). Pathetic.