This movie is actually pretty good. The story is not bad and the acting is not really as bad as people make it to be. Keanu Reeves plays a decent Constantine and manages to maintain the mysterious aura about the character. The only thing wrong about this movie, and it's a big thing for a comic book movie, is that it completely goes against the comics it was based upon...
The movie was designed to depict Christian catholicism and make John out as some sort of exorcist slaying demons and talking to angels. If it's true that in a mainly Christian USA that may attract more audience, it also goes against everything the comic stands for. John is nothing like that, he's never been a Christian in his life, he's a magician.
No religion has favor in the comics, John is capable of talking to angels one day and find himself in the Aztec hell talking to some weird Aztec demon the next day. He doesn't have superpowers and in no way is he a regular hero, he's capable of killing his friends to survive... He's only human, that's what made the comics so compelling.
If it's true that the movie is rather good in his own right, it's also true that it should have no association whatsoever with Constantine or Hellblazer and I'm surprised that the authors allowed them to place Constantine's name in the title...
