MICHAEL GRANIER: This is the representative of an extra-terrestrial civilization. This is the most important discovery in the history of Mankind!
REGINA JACKSON: It may well be the last discovery in the history of Mankind.
Disease probably wouldn't apply to an alien invasion. I'd like to think that humans would overcome alien invaders as they did in Harry Turtledove's World at War series.
I think the reviews pretty much nailed The Day the Earth Stood Still. It starts out suspenseful enough, but eventually becomes predictable, hackneyed, and uninteresting.
You can see this in the trailer below. It's all about the setup, not the payoff. The fun part is getting to the point where Gort the giant robot appears. After that it's like, "Oh, darn...we can't just end the movie here. We have to come up with some lame plot about Klaatu's learning what it means to be human."
Rob's rating: 6.5 of 10.
For more on the subject, see What Would ET Do? and The Best Indian Movies.