One of the best, and most tragic, monster movies of the 80's. I don't know why it seems like some people consider it to be cheesy or corny. Effects hold up EXTREMELY well, it's stylish, and Lance Henriksen is great. The teen characters aren't super well developed, but I've always had a soft spot for this film.
Also the score: www.youtube.com/watch?v=8QIqlYoa7JQ