The special thing thing about this movie is the lack of typical 'bad guys' (Mama is disturbed and overprotective, but also a tragic figure) and the CHARACTER DEVELOPMENT many horror films lack. You end up both feeling for these little girls (who return to civilization filthy, emaciated and feral) and being a little creeped out by them due to the clever writing and the girl's great performances.
The CGI can be a little shoddy and there are plot holes present, but that didn't deter me from enjoying the creepy, emotional, and compelling story. There where some very touching moments and I found myself still becoming uneasy on my second viewing, which hardly ever happens. I found the development of Annabelle's character and her transformation from rocker with no real responsibilities to devoted surrogate mom fighting a jealous supernatural force interesting.
I will now voice my minority opinion and say this movie was better than the recent supernatural thriller "The Conjuring." While "The Conjuring" was perhaps a movie with better visual effects and more audience appeal, it never really got me interested in the characters. They were simply victims, struggling against a tide of bizarre supernatural events that were beyond their earthly grasp.
On the other hand, I felt like the characters in "Mama" were well written and developed, and well I thought the young girls were the highlight of the film, the rest of the cast was quite good too. The child actors display range and prowess beyond their young years, and I hope to see more of them in the time to come.
And then there's 'Mama', who's overall a rather confusing character, but also eerie and ambiguous. You feel for her, and you fear her wrath, in equal measure. I recommend this movie to horror buffs, but also to people who like just a good emotional riveting story. It's not a horror classic, but it's worth watching as 'light horror' for genre fans and scaredy cats alike.