Eh see she wouldn't be near as interesting or well developed had she not made the mistakes she's made, it's all part of her character arc. And who on the team hasn't made a ton of mistakes, cept for Aqualad I guess.
But it's not that I have anything against her, but I prefer other characters. And you have to take into account what kind of mistakes they have done, anyways we would have to hate all of them. If Nightwing is making mistakes is because he has to take some risks for the sake of the world (although I don't like what he did to Arsenal during the last episode), but Megan invaded Superboy's mind, that's something completely different. Even Arsenal's mistakes are more reasonable, and he risked the team's life.
Ah while that is more morally aggreious it was less dangerous to the team overall than the stuff Arsenal did or even the stuff Dick did (though I agree Dick botched that, he should have waited and consulted Superboy and Miss Martian, they are afterall senior members). Really though I don't particularly care what kind of mistakes they made when it comes to judging them, I judge characters based on how well I perceive them to be written mainly. So like I kinda place Miss M and Artemis at the top since I think they are the most fully fleshed out members of the cast. Aqualad and Nightwing are right bellow them. below that my opinions change all the time.