Yea, Larson is a fantastic actor. I really like her. But her acting was a bit wooden. Not 100% of the time, she definitely had great moments. I think a big portion of it was the writers/directors/whomever, didn't really have a firm grasp on what they wanted the character to be. They had a plot, but the character was a bit underwritten, so it was hard to find ways to express her properly.
I think, given another movie or so, they can really find their footing with her. She CAN be a great character, and while they have a great foundation, they need more development to get there.