To lesser degrees, Entrance is much like critically acclaimed Michael Haneke's "Cache." It focuses on the verisimilitude of the medium without using shaky cam or other tricks. Rather than inundating with atmosphere and creepiness, he drains the audience with banality and normalcy. Defying the audience's expectations of a horror film helps to create a vacuum of uncertainty with a hard to place uneasiness.
Where your typical stalk and slash film might rely on popcorn scares to pass the time between kills, Entrance leaves you with nothing. On the right viewer it creates a sense of unsettling voyeurism and begins to wear on the actual conscience. On the wrong audience, it instills boredom and anger for lack of gore/shock/scares/etc - sadly there has been a lot of the wrong audience watching this film after Stephen King praised it in Entertainment Weekly. Not to knock King's typical fans or the readers of Entertainment Weekly, but this is not a pop-horror piece. Its more art-house indie horror than anything.
In recent years there has been a lot of interest in evolving the horror genre past its current state and in that regards Entrance may be ahead of its time. Fans of the ultra-slow-burn horror such as "Red White and Blue" or Ti West's "House of the Devil," should certainly have a profound appreciation for this film. Typical horror fans may only like the final twenty minutes when the pace finally picks up.
I for one immensely enjoyed Entrance, but thoroughly understand how a vast majority of its viewers simply won't like it. I rated it lower than the very similar film Cache due to a few issues with the sound and simply because on a repeat viewing I didn't find all the cerebral stimulation that Cache offers.