A word of advice to modern horror movies: Don't make cute references to Rosemary's Baby, because you'll only look worse by comparison. Annabelle, a prequel/spin-off to the surprise 2013 horror hit The Conjuring, presses its luck by naming its central couple Mia and John (the names of the actors who portrayed the main characters in Rosemary's Baby); while the movie contains quite a few effective scares, there's a wide gulf in quality between this and Polanski's masterpiece.
To quickly summarize the plot (there isn't a lot of it): An expectant couple are attacked in their home by a pair of hippie cultists (the time frame is sometime in the late '60s), then spend a lot of time being scared by household mishaps and apparitions as they slowly realize that a doll of theirs has been possessed by one of the slain hippies. In fairness to director John R. Leonetti, most of those scares are well-orchestrated, with a sense of patience and restraint that are rare among modern horror flicks -- in the movie's best executed sequence, we see the cultists murder Mia and John's next-door neighbors through the couple's bedroom window.
But even though Leonetti brings a great eye to the proceedings and never relies on rapid-fire editing to jolt us, he's still stuck with a screenplay that just doesn't have enough material to fill out the 98-minute run time. In scene after scene, Mia is terrified by an appliance acting strangely or the appearance of a ghost, then recovers once the evil force haunting her has (apparently) decided that's enough for now. That evil doll doesn't seem to have any kind of MO other than to create jump scares that look good in a horror movie, and the characters aren't interesting enough for us to care about them when they aren't being menaced. In a similar vein, actors Annabelle Wallis and Ward Horton (who play Mia and John, respectively) know how to play scared and hysterical, but they're not nearly charismatic enough to supply the depth that the script is missing.
All in all, Annabelle is well-made and contains a few moments that might look great out of context, but its story is too thin to recommend this to anyone but hardcore fans of The Conjuring.