4x21 Headache

This episode was actually entertaining..in its hilarious awfulness.
It's amazing what crap this episode gave us. It is apparent that this season Grimm jumped the shark.
It's only a matter of discussion in which episode exactly.

Kelly Burkhardt would have never been so stupid to let herself being lured in so easily.
Even if she would have, she would have never brought the kid with her. Ever.
Less so would she walk through the frigging front door that is said to be left open while something supposedly happened with Nick that endangers his life. Making an unlocked front door incredibly uber-suspicious, triggering every kind of sense of a Kelly Burkhardt.
But plot needs her dead so we're gonna do everything to get that, even if that means ignoring character traits making that plan impossible in most cases. Something's very fishy here.

When Trubel back then was introduced at the end of Season 3, it gave Grimm a fresh touch when it was needed. Grimm showed its first symptoms of fatigue before that. The more sad (and stupid) it was, when she left the show again. The plots she appeared in were among the weakest of all Grimm episodes but she made it worthwhile nonetheless. Good thing she's back, now that the "let's chase the kid"-arc is basically done.
It's even ridiculous that Mary Elizabeth Mastrantonio, the acress for Kelly, isn't even showing up in the episode she is killed in. What we've seen is a double. Is it because she didn't have the time or because no one thought it'd be necessary paying some respect to the character and the actress? Well, showbiz, it could be either way. Given all, I can't really think positively here, though.

Juliette as a character is burned beyond any redemption now. So, fingers crossed for her being written out of the show in the finale or in the beginning of season 5. Any other attempts would be just the typical back and forth, staying in one spot, not moving the show forward.

It's funny how on zap2it David Giuntoli (Nick Burkhardt) says about Truble coming back:
"We're all 80 episodes in and tired, and she's all like, 'Yeah!' She's a bada** and she's a great actress, and so young and awesome," he says of the 22-year-old Toboni.
David is "tired" of the show "already", oookay. He perhaps doesn't mean it literally, rather that the show isn't that "fresh" anymore and his enthusiasm isn't the same anymore as it was in the beginning but it says a lot about him and how he thinks of this show.
It showed somewhere in the middle of season 3 where his performance got worse and worse and there'll be a season 5 - at least.
As I said before, David Giuntoli is a terrible miscast, only in for the money and has no interest in this show as an actor. Such a shame.

Originally I planned on stopping to watch Grimm with this season but when Trubel gets a bit more screentime in S5, I might watch it just because of her. The only smart move the producers planned this whole season.

From the way things turned out in this ep, i'd say s6 would probably be about Nick hunting down Juliette and her gang as payback. Like the other people who commented below, i too felt that Nick's mum being killed was a rather impulsive move for the producers, it juz felt like they had to get rid of her asap to tie up some loose ends before they end the whole story of Grimm. She just died too fast and furious, we don't even get to see her one last time, at least alive and kicking. Not to mention in the previous eps, when Juliette went all hellbent over being a wesen, i too felt it was a lil extreme how she had a 360 change in her from love to hate just like that. It wasn't really Nick's fault per se, he is the last person to ever want Juliette to turn wesen. He's a grimm for god's sake and he'd know better than to have a human wife turn Wesen. I don't understand why she can't see that unless it's because the producers didn't want her to. Now that Truble's back, i'm not surprised if she dies too in the next season, just so another loose end is done. Well, i guess we all just hafta wait and see~~