First, I must say that most of the low ratings for this movie say "not scary!" The movie may have been sold to audiences as a pure horror movie, but false advertising shouldn't take away from the movie for what it is: A found-footage movie about a group of friends (one way more than the others) who go to great lengths to break into Area 51 that should be classified as a suspense sci-fi movie; definitely not horror.
A great portion of this movie is about the set-up of these guys (and a girl) getting ready to sneak into the lower levels of the base, which I can see how the average movie-goer could scoff at. If you go into this movie hoping for action, I'm sorry. Though it isn't what many were expecting, it is still very interesting to see their plans unfold.
The third act is where it really surprised me. Oren keeps with the golden rule of good horror: waiting for the unknown is a lot scarier than finding the unknown. You see very little of the aliens, which could be a let down to those looking for a monster movie. But watching the shadow of the aliens walking down the hall, or seeing an alien slowly slide from the darkness is truly creepy. There were many times I was very tense and on the edge of my seat.
The ending isn't as bad as many people are saying, for I kind of liked it. With some slightly better writing/imagination towards the ending, it could've made this movie a true diamond-in-the-rough. The acting, despite what many say, is tolerable and, for the most part, believable. The main character does have these moments of awful, goosebumps- inducing acting, but the other elements of the movie made me forget about it.
All in all, give it a shot. Its streaming on Netflix, and I'd say its well worth a shot. Worst scenario, you lose an hour and thirty minutes of your day. Or you could walk away with a pleasant experience. Just remember to keep your mind open to what the movie wants to be, not what you want it to be. Have fun!