It certainly doesnt aide your thoughts on the movie by knowing the critical impact point aforehand...
but, I dont think either that by that fact alone your other notes on it would be affected as well.
I enjoyed this movie, thought the editing was done well, the acting supurb and the story refreshing for a new twist.
After viewing the movie in its entirety I define it more as a phsycological thriller rather than violent.
Regarding your thoughts on the terrible picture of mental health...well, it aint pretty
REally though, there are many forms of mental health and also many forms of depicting that, I think this film just walked away from the norm on that and as well, I found that refreshing.