Well the take I've been hearing about this series is that it is "Fables done Buffy style." After seeing it, I can agree to the basic truth of that thought. However, I do see some potential here and honestly I had some fun watching it.
The plot is pretty simple. A cop suddenly starts seeing CGI on people's faces. He learns from a dying relative that he is one of the last Grimms, people who can see the secret monsters. He's given some weapons and some books and now he has to figure out how to stop monsters. Is he suppose to arrest them? Kill them? Are they even all evil? One of the monsters he meets is "reformed," and actually helps him.
Overall I liked the show. It didn't take itself too seriously, and avoided getting nutty with the back story like "Once Upon a Time." I could definitely watch this every week.