Those underdeveloped characters become more of a problem when the plot starts to run into the realm of the indestructible bad guy and a shocking twist I found lazy and in poor taste (even in this realm).
Don't breathe is one of the most intelligent films of the year, one that from the angle of horror, invites the audience to perform reflexive exercises around morality and justification of the lowest human action. [Full review in Spanish]
The suspense is built as carefully as it is in a good John Carpenter movie; Alvarez uses the camera like a stealth weapon, exploring dark corners and hidden areas of the house with devilish glee.