Following in the footsteps of movies like "Underworld" & shows like "The Walking Dead", for some, "Grimm" is an acquired taste.
Personally, I like the show, despite the leaps of faith one simply must take to accept the sometimes laughable emphasis the show places on police procedures.
The characters are likeable, the writing is quite good & the entire concept is highly creative. Just as anthropology is discovering that history doesn't quite jibe with what we've always been taught, "Grimm" puts a neat spin on the classic fairy tales.
Is it for kids under age 14-15? No, it isn't. So if you're a parent who allows the TV to be your babysitter, you're going to be in a bit of trouble.
Much like "South Park" which caused an uproar back in the 90s, despite its blatant opening disclaimer, "Grimm" is designed for older teens & adults.