Yeah, a lot of things went wrong, but in the end, the storylines didn't lead to (what I felt was) the natural conclusion, they just ended up nowhere.
For me, I don't think season 3 drained my love at all (because it made me think and in many ways the characterizations worked for me), but everything surrounding the show killed any desire I had to talk about it.
I think Veronica's characterization in early season 2 could have worked if it had all been her repressing the past two years as if they'd never happened, but no, they just completely screwed up the character for no reason.
I think KB can do a great job, but it's not like she'll stand out if she's off a bit. Heroes doesn't exactly have the most stellar cast (though some are excellent), I mostly just watch it because I think it's fun. =)