She was in her prime in Kanto and the Orange Islands. She was funny, entertaining, had an interesting dynamic with Ash and Brock, etc.
But as we know it all went downhill from there. I love the fact though that the writers knew they were running her character into the ground, and in an attempt to save her, they revived her character and established her as the Cerulean Gym leader.
It's funny because Misty came full circle. Originally she ran away from the Gym and her responsibilities because she was too immature, but now after some character development, she's become the Gym leader and has established herself with a new career and a sense of importance.
It's great that they managed to save her character in AG, and hopefully they'll keep her on track, rather than bombing her again by taking away all her character development and her new focus on life by bringing her back on the cast. Since that is unlikely to happen anyway, Misty should be A-OK.