Not crazy about that development either, Laurel is the worst thing about Arrow while Sara was a lot of fun and actually likeable. Not the best trade-off, IMO. Having her return only to be killed off again right away, really?
And while seeing Roy in the field was great, he barely said two words throughout the episode, not even when Thea was mentioned. Hope he gets some spotlight soon. Diggle, too... the parent plot is cliche and uninteresting, it was clear from last season that the writers had no idea what to do with him anymore but this not the way to go.
Still, I enjoyed the episode overall. The interaction between Oliver and Felicity is always fun, and the Hong Kong flashbacks are an interesting change of direction (although Waller hasn't told Ollie yet what she needs him for after nine escape attempts?). And this new Count Vertigo was certainly better than the previous one, even if the new effects of the drug makes him look like the Scarecrow instead and I couldn't understand a single thing he said.