This is going on my list of movies that I want people to avoid. No way am I ever going to recommend it.
Basically, this character called Darkside comes in to a 1984-style Tokyo through a hole in the ground, causing...umm...errm.....ahh...ummm....some things to happen. None of it is fully explained. However, unlike 2001 and Blair Witch 2, where some of the appeal comes from the unexplained, this movie is a confusing waste of time.
We are given potentially interesting stuff that just sits there inert for the whole movie. Never once do we hear a basic explanation of the impact that bad dreams have on our life. And we'd like to. And what on earth does it have to do with the movie? Nobody knows, and by the end of the movie, nobody cares.
Watch Evangelion instead. At least that can be explained.