Depends on what you're talking about. Did I know it was the season finale? Yes. 
Did I know that it would be Marissa who died? No way. I thought it would probably be Julie Cooper since she's not really a super important main character. I was shocked. I kept saying "She's not really dead." but then they showed some of the stuff for next season and it seems like she is.
I was kind of getting sick of the Ryan/Marissa show, but I didn't want her to be totally gone! I guess her little sister will be taking her place next season.

She nice, the Syren.