Here are some ideas:
It is not an objective critic of the movie, but rather a description of what you felt watching the movie.
You should not hesitate to write more about your emotions than about the movie itself.
And take care not to divulgue any information about the plot!
But in the end, other users are the one rating the comments, so you may do as you feel it should be done.
Samuel L. Jackson
Robert De Niro
Adam G. Sevani
Jon M. Chut