... Originally conceived as a Web series, the 84-minute pic is divided into 10 installments, presumably for online-friendly viewing. Yet far from feeling patchy or episodic, "Sound of My Voice" has a killer narrative thrust that plays well on the bigscreen, the chapter numbers serving less to offset individual vignettes than to chart the central characters' disturbingly swift assimilation into a dangerous sub-subculture.... Marling transfixes as a gorgeous but alien-like figure who draws her dominance from an outward display of sickly vulnerability. The film's title is an apt and evocative one, as this charismatic leader speaks in a voice both gentle and warm, even as it thrums with understated menace. Denham and Vicius are fine in detective-duo roles that could be more richly elaborated in future films or series. "Sound of My Voice" is an economically assembled film that knows what it's doing at every step, and Batmanglij appears to have channeled his limited resources for maximum effectiveness... The tease of an ending... leaves the viewer wanting more not just from the story, but from a new filmmaker of considerable promise.
... everything is intricately tied together into one unbelievably engrossing narrative that keeps you guessing until the very last second (and possibly beyond). Is Maggie from the future, or is she simply scamming everyone who crosses her path? That's the biggest question in the film, and Marling -- along with her co-writer and first-time director Zal Batmanglij -- provide the most brilliant answer that will have you talking long after the end credits roll.
... The film is deliberately sketchy and impressionistic. You get snatches of backstory about the two infiltrators and Maggie relates her own story, to be believed or not. The actual intent of the cult and Maggie’s plans remain hidden. What is clear is that the filmmakers are not going accept the couple’s cynicism. Instead they raise the possibility that Maggie just may be telling the truth.... This is speculative fiction that goes a step or two beyond The Twilight Zone. It’s not reality stood on its head by surreal events but rather a reality where not all is seen or revealed, where other realities may exist....
... Using a chapter-based structure and littering the story with unresolved details about Maggie's origins, the director plays up the situational intrigue to a consistently provocative degree, maintaining a creepy feel from start to finish. His characters' talky, self-serious mannerisms sometimes hamper the overall impact of that atmosphere, but Batmanglij holds it together with tantalizing questions about the nature of the cult....