Brie isn't the problem. Imho the movie has an editing issue...meaning, it cuts away from scenes so fast, that it is very easy to miss her nuanced acting. It really does her a disservice. My other big criticism of the movie is the use of music. Honestly, why not add a badass sound with a con air style guitar riff? This is supposed to be the 1990s, right? And if you want to use songs, pick something which actually means something to Carol.
But technical issues aside, I love this movie. To be fair, it is the kind of movie one has to think about a while to realize how brilliant it is. Thematically, it is really, really strong.
And I like Carol as a character. She is stubborn, a little bit arrogant (which I love because female characters are so rarely allowed to be arrogant on screen unless they are the villain), she is an absolute speed junkie, she is an idealist (remember, her main goal in live was always to do something "which matters"), she has a really dry humour, she is cheeky and I just love her little smirk. She is also good with kids.
I can't wait to see more of her.