First of all, if you're not familiar with the story behind Constantine this is going to be an extremely confusing experience. Constantine is the story of a John Constantine, a troubled soul with a troubled past. Unfortunately the game gives little if any history of who John is and why he possesses unique talents. Since this isn't the place to back fill the story of Constantine, I'll leave that to those interested in finding out on their own but I can tell you that it's a bad sign for the rest of the game and is one of many problems that plague this it.
Constantine is a third person action game that meets the basic requirements for a game in this genre. John can shoot enemies and cast simple spells but the entire gameplay is straightforward and requires little effort to navigate. Even casting spells, which on the surface attempts to deepen the gameplay, is more challenging to mess up then get right, as you only have to hit a series of buttons in order.
The cut scenes are actually decent along with the rest of the graphics. Some of the environments are more on the drab side but definitely one of the better aspects of this game. The audio doesn't come across quite as well but the sound effects are well done.
If you're familiar with the comic books or loved the movie, Constantine may be worth your while. The story is a lot easier to follow if you know the character's background and even gives a good reason to see how it ends. However, for the rest of us, its going to be a struggle and there are plenty of other action games out.