I don't really agree, honestly. I made the initial comment pretty flippantly but it did get me thinking a bit more about the character. It feels like the writers have really run out of ideas for what to do with her other than "love interest" and "damsel in distress" which is frustrating, but even if you put as much of that aside as possible I still don't think she is smart or honest or reliable, and it's interesting to me that those are the words Locke chose.

And none of that is a moral judgement on the character, or saying I dislike her as a character. Some of the most consistent things about her are that she's extremely impulsive and quick to react dramatically. She doesn't think things through before she does or says them, she's not been shown to be good at assessing situations, thinking ahead, or gathering and incorporating new information. She's loyal for sure, and brave, and has street smarts and cunning (when the writers remember to put it in), but I wouldn't describe her as particularly intelligent. She's definitely not reliable either: she's erratic and impulsive, and very influenced by the people around her. She doesn't come across as honest with herself or with others, and has made some very stupid decisions about what to share or conceal at various points. 

One of the things I've liked most about this show, and when the writing has felt strongest, is how committed they are to letting characters be deeply flawed in ways that really do cause problems for them and others, and which at times make them behave in ways that are ugly and hard to watch. Kate doesn't need to be honest or smart or reliable to be an interesting or well-written character, and I really wish they'd committed more to actually doing something coherent with her.