I liked it a lot despite a few flaws. (Spoilers)
1. Maudlin ending;
2. The boy could've been a little spookier, like the kid in Babadook. That kid've been perfect for this role.
3. If he was able to liberate the social worker from the chrysalis, how come all the other people weren't "liberated" and showed up. Where did they end up? Locked up in his mind?