I love scary movies, and I really love "scary" movies-- from Blair Witch to Paranormal Activity, I've always been a huge fan of shaky cameras and found footage. Ghosts and aliens scare me, and classic terror tropes work wonders on me! Things jumping out from behind other things and unexpected screams are my idea of a fun movie night.
If you are looking for a scary movie with aliens as the focus, I would recommend picking up Dark Skies, or John Carpenter's The Thing... but not Area 51, because this is a terrible film. I put it on expecting to be shock-scared, or at least creeped out... but all I got was progressively more and more annoyed.
The first half of the film does absolutely nothing but establish that the viewer should lack empathy for the main characters-- they are vapid young men who enjoy drinking, planning ineffectively, and disrespecting professional entertainers.
The second half of the film is meant to heighten the viewer's anxiety and presumably scare us, but it falls disappointingly short in that respect. Instead it devolves into lots of running and flailing, lots of awful camera work, and terrible physical acting. When the end finally comes, it's more a relief than anything else.
The only positive thing I have to say about this movie is that the main characters' treatment of their female colleague was basically respectful, which is more than what I can say for most movies that are structured in the "x number of guys + 1 girl" model. Nobody grabs her breasts or calls her disgusting names or belittles her intelligence based on her gender. That's awesome.
The rest of the film? Really not so much.