I really like Grimm, but I keep wishing they would make it a little more "Buffy the Vampire Slayer-ish." He looks through those books, but other than a brief conversation with Morgan (think that is his name) we never really learn much about the creatures. Sometimes it just a cop show with a little supernatural thrown in and it could be SO much more!
I think as the season goes on (and the rest to follow) more will be explained, I kind of hate the jumping from one to the other too. Hopefully they pay attention to their fan base and mold it to suit everyone's needs.
It is only the first season. I'm sure that by season two everyone will have a better grasp of what they want and what to do and where to take it. The first season of Buffy wasn't great, but it certainly got going and comparably better. It just takes a while for the cast and crew to really get into it sometimes. I feel that Grimm will get better.