NEW FAN HERE!
I marathoned the first three seasons of Grimm over Christmas holiday, and all of the first half of season 4 over the last few weeks. Great show!
My favorite season might still be the first season, when it was just the Nick and Monroe buddy cop series and the silly Royals plot hasn't taken over the show yet.
I love all the main characters except for Juliette and Adalind, not sure why Juliette is still on this show. Her whole amnesia plot was a chore to sit through in season 2.
Also I find Adalind much better as a reoccurring antagonist that appears only in a few big episodes in a season, her European adventures and baby plots have been really dragged out. I feel like the producers love Claire Coffee too much, and gave her the inane plots just to keep her in the series. A mistake in my opinion, the actress should have just been kept as a reoccurring character.
I didn't think the show would last during the first year. It seems like it is really hard for fantasy or Sci Fi shows to last these days. I only jumped aboard after getting the first three seasons over the holidays. It is a shame the show is not more popular. But at least it has survived so long because keeps getting good ratings for NBC on Friday, while amusingly all the more popular "brand" name shows like Dracula, Hannibal, and Constantine have failed in that department.