Here be spoilers.
Pros: Moar hurt!Isaac, awkward and funny Stiles making plans, Scott still being awesome (yay for character development), Derek's still being all protective, PETER, DANNY, COACH FINSTOCK, one of those alpha twins is gonna go for Danny (I feel like poor Danny boy's gonna get his heart broken...), MISS MOREL IS EVIL?, Allison being redeemably awesome, detective!Stiles, Stiles almost getting laid which he totally deserved so I wish it had happened, that friend of his was awesome, I'm sad she's probably dead but happy that Stiles is most likely gonna get in trouble for her death, because that would create delicious angst, WTF IS LYDIA?, ONE OF DEREK'S SIBLINGS IS ALIVE THANK FUCK HE TOTALLY DESERVES HAPPINESS AND SHE BETTER NOT DIE!!!, the alpha alpha is actually blind which I thought was cool, there has been more Sterek scenes this seasons than I thought there would be going off interviews
Cons: So many elements to the story that it felt a bit out of focus, looks like awesome new girl from the last episode is dead, and Erica is dead *cries* and I think the next time trailer had an image of Derek holding her body which broke my heart (this isn't really a con I guess - they were working with what they had), not much of the parents at all
PS: If anything bad happens to Derek's sister, I will throw 82390543 tantrums