I'm starting to really like Mariner as a character. Yes, she's rude, cynical and kind of all over the place but she's smart, good at solving problems on the fly, can kick ass and is a really, really good friend. Isn't that the kind of crew member you want on your away team when it all goes sideways? (Well, except for the fact that she probably helped it go sideways. Hah. No one's perfect.)
It appears that at least some of the problem solving she learned from her mother. I liked the Captain getting to the last set of issues and finding out that there were only 2 people left blocking the mission, and immediately blowing the moon up.
I still dislike the style of the animation. It figures that I finally get a couple of interesting female Star Trek characters where I can't wait to see their backstories play out (the mother/daughter dynamics are a nice change of pace from all the guys with daddy issues I've had to watch over the years) but the visuals are distracting. That Cartoon Network feel doesn't do justice to the characters, imo. The ships and exteriors are amazing though, as others have said.