It appears Once Upon A Time is not the only new show coming out lately that has a slight fairytale theme to it. While Once Upon A Time seems to be just a mix of fantasy with drama, Grimm is both those and more - mystery and thrill!
It is a very interesting mix of things, and if I were to explain it in terms of other TV shows that I have watched (keeping in mind that there aren't that many), I'd say it's a slight hint of Bones with a strong side of Buffy the Vampire Slayer. This isn't too ridiculous of a thought since the executive producer of this show was also the producer for Buffy the Vampire Slayer and Angel! (Yes, I researched it a little. Hehe.)
I wouldn't know, but are there any other shows out there already that have a similar plot line? In any case, I am currently anticipating the second episode so I can get a better of idea of which direction the show is headed. Can't wait!