Well, that sucks. I just watched the last episode of Grimm. It was one of the best shows on tv, definitely the best supernatural genre show. I'm not sure, since I didn't bother to research it, but I don't think they originally planned to have this be the last season. At the beginning of the season they had the whole Rosalee finds out she is having multiple kids and that they might be special or different somehow, then that whole thing just got dropped. I'm think that was supposed to be a main story arc for the next season but they found out part way into filming that no next season was to be had. They also hinted that "Eve" was once again "Juliette" and in love with Nick, but that just got dropped as well.
The finale was ok. It had lots of action and got the whole cast involved, and they wrapped it up with a happy ending. But... it just felt kind of like a let down for the show to end. They could have done so much more with this show. After all, Supernatural just keeps chugging along season after season, and Grimm has just as much story potential and much more interesting characters. (Which isn't to slam Supernatural, that's favorite of mine as well, but Grimm really did a better job fleshing out its charters and making you care about them.) I wish Netflix or somebody would pick it up... but the way they ended it, it's probably not very likely.