I'm still so confused about Claudia! I have a theory that maybe the Wild Hunt is making the Sheriff think that Claudia is still alive to distract him so it would be harder for him to remember Stiles. Since he and and the Turners seem to be the only ones who could see the Ghost Riders, maybe they were taken for a specific reason? And we know that their powers aren't infallible, since Corey's powers can make relics that they left behind visible to the naked eye so that they can trigger their suppressed memories, so maybe this was an attempt to make it less likely for Stilinski to figure it out-- I could easily see the Ghost Riders underestimating the bonds between Stiles and the McCall Pack, but Stilinski and Stiles have been all each other has for so long that I could see it being hard to completely erase the memories they share.
I really liked learning more about the Ghost Riders though, and Corey's connection to them. I'm still eager to find out how Parrish is connected to them, too. Also, why do I get the sense that Der Soldat is associated with them as well? I feel like it can't be a coincidence that he just happens to be teaching them about physics concepts that are helpful in figuring out how the Ghost Riders' powers work.
As for Stiles, he's definitely missed, but I don't know, I kind of liked that his absence meant that we got more screentime for Scott, Lydia, Malia, and Liam and their friendships with each other, which can often be lacking. I loved Scott and Liam's lacrosse captain side-plot being a metaphor for being Alpha of the pack and how leaders can't give up or blow things off, and Malia's inner coyote is so endearing, I don't even know what else to say about it.
Also, where the eff are Melissa and Argent? I miss them so much.