Wow...I loved it. (Spoilers)

Such a great alien movie!

I find Calvin a lot scarier than most sci-fi creatures we've seen over the years.

The twist ending was perfect. Although Jake Gyllenhaal should have been dead by the time he hit the sea. Nobody survived an encounter with Calvin for more than a minute or two.

I would have ended the movie with another twist... Calvin reaches earth, but becomes inept and incapable of moving because of gravity.