If you take it as a movie about the crossroads of one mans life, as he deals with deep issues that everyone confronts sooner or later, it's an excellent movie. All of the characters really click, and without any intrusive explanation, you begin to understand the characters and feel for them.

If, however, you try to get into the science fiction element, you'll probably be disappointed. The movie is a good horror movie, but it really fails in the science fiction regard. The plot feels a bit contrived, and especially given the ending, very forced.

Having said that, it's not a disappointing movie. I rather enjoyed it, and really enjoyed seeing some characters come to life so well.