How did critics love the movie Salt?

It was a really great concept, I have to say. Jolie was great, but seriously- the storyline was so unrealistic, I just wanted to punch the screenwriter in the face. Basic synopsis: Evelyn Salt kills like 100-something people including the president of the United States (by herself, I might add) while she tries to escape conviction after BETRAYING HER COUNTRY (with no master plan or anything- just by beating people up). Finally when a dude catches her, he's basically like "Get outta here, ya little rascal. Just don't do it again." and watches as PUBLIC ENEMY #1 escapes.