I liked the demon
One reason I liked this film is the the demon, I thought he was genuinely creepy! But I think perhaps viewers didn't appreciate him/it in the film as it deviated from the Doll and the Annabelle ghost.
the Basement scene is horror cinema gold I feel...... BUT maybe he should have had his own movie... I think he was better suited to the Insidious franchise or similar with him terrorising families.... without the need for a doll.
oh... and he was played by the same guy as the lipstick demon in insidious!