Mixed feelings - Spoilers

I've watched it a couple times and at first I really liked it, but as I thought about the premise combined with the ending I liked it less.

I love Headley in this. I thought she did a great job portraying a confused, traumatized woman trying to make sense of what was going on around her with only a fragmented memory at her disposal. I didnt mind the pacing and found many of the scenes thoughtful and overall adding to the movie. For example, the diagnostic tests were a clever way to introduce us to the mirror image concept and lay a foundation for how long this has been going on. I can see why others wouldn't, but hey that's why we dont just have vanilla and chocolate.

On reflection what I didnt like is the seeming inconsistencies between the mirror people, her character, and the sudden speed up with what was going on. At one point they reference her suspected condition and that there were only 100 cases documented since 1923, but 80 of those were in the last decade. Similar point with the reversed heart, only 1 in a 1000. Assuming that her "condition" is other similar cases of a mirror person taking over a body it looks like the process has started speeding up, but is still proceeding at an extremely slow rate. In this case her friends and family succumb to it in a matter of several days. That's a small part of it though.

My biggest complaint is the mirror people being susceptible to a blow to the head. Sure it works for the movie for the doppelganger to think she's the original, but to not only erase her memory, but to alter it's personality as well seems pretty far fetched. This isnt Michael Bourne it's a fricking thing that came out of a mirror. Then it sees the original dead and suddenly it's back to being a diabolical mirror thing? Seems like a stretch. If they are enough like the original to feel fear, fright, love etc what's the point of killing the original? I mean who cares if suddenly there are two of everyone walking around? Sure it would freak me out to know the other one of me came out of a mirror, but I could live with that. Which brings me to my last issue.

What's the endgame here? Quick, destroy all the mirrors? With aliens I get it, they want to wipe us out. With mirror people I'm missing it. Can they have kids? Do they need to keep humans around to have kids to let more mirror people out? Can they not exist in this dimension with the original still around? What's the plan if they wipe out all humanity? Sit around and do all the stuff we did?

All in all I still like the movie, but I dont think the end was very well thought out.