That wasn't too shabby a finale, considering how uneven and disappointing Sleepy Hollow Season 2 was overall.
I do wish they had come up with the time traveler spell sooner and the characters had spent more time in the past. This was one of the best creative ideas the writers had all season and it came at the end, Sleepy Hollow Season 2 Episode 18.
Although I figured (and even wanted) Katrina to go all evil, it felt rushed and almost like fan service, didn't it? You want her to be bad and you want her dead, here you go. I'm not sure that was the original plan for the character but, c'est la vie.