I really like the way the first season turned out. I was thinking of dropping the show early on, because the early stories were uneven and the secondary characters were all more entertaining than the main character. But Monroe was so delightful that I kept watching.
By the end of season 1, Nick has really grown, from a reluctant rookie, to a dedicated warrior/scholar. And it is clear that Nick can continue to grow: in skill, in leadership, and in knowledge.
I hope that they continue to grow the secondary characters along with Nick. Monroe (still my favorite character) has really gotten into the Grimm stuff, and he is the reason that Nick has kept his balance with all the weirdness and even started to enjoy it. Juliette has grown, too, despite only seeing the shadows of how this world works instead of the actuality.
They all have the makings of an excellent team with Nick as the captain. Monroe and Rosalee have already shown how important they are. Juliette is valuable because of her veterinary experience in such a wide range of animals: she would be able to act as an emergency doctor for Wesen as well as people; and her aptitude with firearms will no doubt come in handy. Hank's and Wu's skills and connections as policemen would certainly be valuable. The Wesen they have helped can act as an information net and backup skills. (I don't see Renard as being on the team: he will make either an occassional ally or an interesting enemy.) As the characters come together as a crew, I expect their byplay and interactions to get even better than they are now.