Sometimes it's impossible to separate a film from your first experience with it. I remember being in college watching Signs in early 2003 when everyday there were "high" probabilities of catastrophic terror attacks. Watching the film about a beleaguered family facing down an alien invasion, a threat from an unknown source, matched the jittery moment. Much of what the family learns of the invasion is from the television, an eerie reflection of the uncertainty after 9/11. Like a great Twilight Zone episode, Signs builds character and relationships with with cinematic technique.
M. Night Shyamalan had the makings of being the next Spielberg in 2002 (unfair label to pin on any director), with three solid movies in his filmography, until a series of misfires sidetracked his career that's hopefully back on the upswing. Signs may be his best film to date in my opinion, no thanks to the two male leads Mel Gibson and Joaquin Phoenix as unlikely brothers defending the farm. The two kids were excellent as well, Rory Culkin and Abigail Breslin.
Like Spielberg, Shyamalan makes the everyday mundane mystical and profound. The ritual of the dinner table, the art of storytelling, and and the pathos of an absence brings with it (in this case the mom). Reactions are realistic, there's a cheerful banality to the dialogue. A little bit of Norman Rockwell, but also a sense of darkness in the heartland we get from Stephen King. And the emotions are genuine and real, no moment rings false. When the family goes from arguing to group hug, on paper it might appear silly, but the actors made it work.
The immediate post-9/11 vibe of Signs appears a bit trite now, it was mere prologue to the hyper reality of today. Signs still stands on its own as an effective thriller with elements of horror that plays the audience like a piano.