This really felt a bit too rushed. Especially the part with Constantine on the island. Felt really shoehorned in to explain why Oliver knows Constantine. Wish Ollie would have met him during a bigger crisis, so he can see more of his abilities, instead of just seeing abilities that amount to being parlor tricks. "Hey, this Sting looking dude can break out of handcuffs and find trap doors, bet he can restore souls too." But Matt Ryan himself was still amazing. We definitely need to see more of him. If not on Arrow, hopefully he appears on Legends of Tomorrow.
The whole Sara arc didn't do Laurel any favors. It really made her completely unlikable again, until halfway through when she finally apologized, for what she did. But before that, when she was interacting with her father, she pretty much acted like she lost a cat. "I've been looking for her." You know, I'd sound a bit more concerned when my resurrected sister got loose and is killing people around town. The best part of course was when she tried to defend herself. Oh, the reason you didn't confide in Oliver was because you wanted to avoid his judgmental look? That's nice. People are dying, you crazy woman! Also love how it suddenly was all about her again. "You don't see me as an equal. You didn't tell me about Thea. You didn't tell me you were the Arrow! You didn't support me being the Black Canary! Wah! wah! wah!"
Now that Sara is back, hopefully the writers can go back to giving Cassidy decent material, or at least relegate her to subplots where she isn't getting a lot of focus.