My problem with Teresa isn't her looks or even her acting. It's the character. I just have a very hard time buying into the Teresa character. There's just something about her and how she is presented that doesn't really fit for me. She certainly doesn't fit with the Scoobies. Send her off to spend time with Dear old Mom. Or let her take to the road to wage her teenage angst fueled war against Wessen in the seedy districts of some city far, far away.
She made for an interesting distraction, especially since the show seemed to be going pretty much nowhere for a bit. But after a handful of episodes I am done with her, especially since many of her actions stretch the bounds of plausibility, even for this show.
I'm all about a Monroe/Rosalee storyline that gets more attention. And I do have a vested interest in Wu's development. Teresa though, only active Grimm or not, just really doesn't fit for me. Nick was a rather competent detective long before he was a Grimm. He also hasn't forgotten everything he knows about Wessen, or how to handle himself. He's simply more "limited" now. It will be quite sad if Nick is suddenly worthless simply because he doesn't have his powers.