Bob, the big difference between Shrek and The Day After Tomorrow is that one roots itself in pure fantasy, while the other tries to root itself in fact. Tomorrow tries to send a conscientious message to the viewer that this is a possible consequence to our actions, which is what is supposed to the give the movie emotional value. You're supposed to truly fear what you're seeing because it could actually happen.

Only...it can't actually happen.

Granted it is a movie, and it is fiction. But the fiction in the movie tries to root itself in scientific fact, and it doesn't (apparently) do a very convincing job of it. That kind of strips away a lot of the weight that this movie wished to attain.

I'm basing everything I've said solely off of trailers and opinions I've heard from other peeople. I haven't made any comments about the acting, or the cohesiveness of the story. I'm just pointing out that the entire fear element of the overall plot is blunted by the mechanics of the situation. Hopefully, the directors were intelligent enough to realize this, and instead chose to focus to fear-building elements off of individual character dilemmas rather than the entire apocalyptic picture.