Potential spoilers below.
So, the big finale. I had done my best to avoid spoilers although I had read that both Jonas and Armitage would be leaving the show.
What we have is an episode that on one hand finishes the story and on the other hand it starts a new chapter. (I'm assuming the show will return, but what do I know.)
In short Robin, Guy and the Sheriff don't look like they will be returning. And I would assume that Isabella was also standing a little too close to the Byzantine fire, but fingers crossed that she survived.
In the end Isabella did turn into a boo-hiss type villain. I had been hoping that she would show a little bit of subtle horror at the path she was taking, a little bit of remorse after stabbing Guy or scratching Robin with the poison blade. Lara is clearly a good enough actress to show that.
Right now I don't feel like doing the whole screen grab type image thing so here's a photo of Isabella in episode 3.13. Note the poison bottle around her left wrist!
Ah, Lara looks nice with her hair down...