I don't like Misty.
Too mean in season 1.
Too bland any other season past season 1. o_O;
I mean, maybe there's something i'm not quite 'getting' about her, but that's how I see her character.
Eh, she wasn't really that mean in Season 1. Believe me, she'd need to yell "pervert" and beat up Ash just for either walking in on her changing/bathing at the absolute wrong time (even when such was a clear accident on his part), beat him up when she walks in on HIM changing, or heck, force him to see flesh before beating him up anyway before she can qualify as "too mean" in ANY season, let alone Season 1 (you know, like Naru Narusegawa from Love Hina, or, heck, any of the Hinata Inn dorm girls in the same franchise, and how they treated Keitaru Urashima that whole time). Heck, Bulma was a lot meaner to Goku in earlier seasons of Dragon Ball than Misty ever was, and she's one of his best friends.
And to be fair, it's not like Ash was all that great in Season 1 either, starting plenty of arguments with Misty and being about as snappish and mean to her in turn, not to mention exaggerating any accomplishments he had. Heck, one instance, he played a very bad joke where he claimed he was "feeling a bit like a ghost himself", resulting in Misty, Brock, and Pikachu understandably being very angry with him (especially after this came right after Brock, for justifiable reasons, screamed at the top of his lungs due to grabbing Pikachu's tail by accident and Pikachu reacting). And I definitely remember Episode 3 had him basically siccing his Caterpie on Pidgeotto, which even regarding his being a newbie, there was no excuse there for not knowing Pidgeotto would try to eat it, and thus nearly got it killed. In fact, Misty's telling him off various times, while admittedly harsh, was actually for the most part deserved on Ash's part, and even the few times she DOES end up telling him off when he actually didn't do much wrong, her reasoning for assuming he did a bad thing was quite understandable (case in point: in their first meeting, Misty slapped Ash for endangering Pikachu and trying to drown him. While we know that wasn't actually the case, Misty had no way of knowing that Ash if anything was trying to save Pikachu from a flock of Spearow that Ash had unwittingly provoked, not to mention Pikachu was partly at fault because the latter's disobedience was ultimately the reason why Ash tried to throw a rock at Spearow in an attempt to capture it and thus started that whole mess).
Can't comment on anything post-Season 1, though, mostly because I'm not sure how to counter "bland."