This review may contain spoilers. I can handle the truth.
I like how the ending is left up to you... I think there's a lot of meaning behind the camera pan over to the window in the last shot.... I personally believe that it hints at Rosemary's fate - she's going to do exactly what the last girl did and jump out of the window to destroy Satan's baby. It's either that, or she settles in and starts hanging out with Ruth Gordan and her weird friends, and I don't see that happening any time soon.
Jump for it, Rosemary.