I've read Unspoken and Undeclared. For " new adult" they're pretty good. They might not be high literature, but the writing is very readable (IE I didn't feel like I was losing brain cells while reading them). They have subject matter - underground fighting etc. - that, while I've heard of said subject matter, is not part of my life, and it's a nice escape from the snot and poop and Cheerios that is my life.
And at fiveish bucks an eBook, they're totally worth it. I see she's got a new one or two available. Bottom line - I'll buy more Jen Frederick.