It's a full-on horror movie, and one that owes more to William Friedkin's "The Exorcist" than to anything Raimi has done (possible exception: "Drag Me to Hell").
It's from the "Exorcist" that Alvarez gets the idea of grounding the movie in a serious reality - the "Exorcist" played on secular/religious tensions (and every parent's understandable fear of their own moody teenager).
In the "Evil Dead" reboot, five friends go to a cabin in the woods, but they are - atypically - not there to waste time and get high. In fact, the very sober purpose of the retreat is getting clean - the remote location has been carefully chosen as the site of a cold-turkey withdrawal for a young woman (Jane Levy) whose recent closecalls with an OD have led her brother (Shiloh Fernandez) and friends to take these extreme measures.
Elements from the original remain - the cabin contains an accursed, occult book, and when it is opened and read it unleashes a spirit, that, as it happens, inhabits and possesses the girl in the throes of withdrawal.
In the confusion - is she enduring withdrawal or something else? - Alvarez has room to sustain his premise while pushing the movie into gorier regions, before accelerating to a violent bloodbath.
Again, it's not funny, in that Sam Raimi way. And there is no wild card in the cast, like Bruce Campbell. The Stooges-style laughs are few and far between (though there are in-joke visual gags for buffs), and the movie has the modern taste for clinical dismemberment and shock. I don't mind seeing a girl go on a stabbing rampage with a hypo, but must she first lose control of her bowels?
This is really not my cup of tea, but I like the way Alvarez grounds the movie, controls the tone and keeps track of his ideas from beginning to end (watch out for jumper cables!). So does Raimi, who's already hired him for the sequel.